1
|
Hariki A, Dal Din A, Amin OJ, Yamaguchi T, Badura A, Kriegner D, Edmonds KW, Campion RP, Wadley P, Backes D, Veiga LSI, Dhesi SS, Springholz G, Šmejkal L, Výborný K, Jungwirth T, Kuneš J. X-Ray Magnetic Circular Dichroism in Altermagnetic α-MnTe. PHYSICAL REVIEW LETTERS 2024; 132:176701. [PMID: 38728732 DOI: 10.1103/physrevlett.132.176701] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 02/01/2024] [Accepted: 03/20/2024] [Indexed: 05/12/2024]
Abstract
Altermagnetism is a recently identified magnetic symmetry class combining characteristics of conventional collinear ferromagnets and antiferromagnets, that were regarded as mutually exclusive, and enabling phenomena and functionalities unparalleled in either of the two traditional elementary magnetic classes. In this work we use symmetry, ab initio theory, and experiments to explore x-ray magnetic circular dichroism (XMCD) in the altermagnetic class. As a representative material for our XMCD study we choose α-MnTe with compensated antiparallel magnetic order in which an anomalous Hall effect has been already demonstrated. We predict and experimentally confirm a characteristic XMCD line shape for compensated moments lying in a plane perpendicular to the light propagation vector. Our results highlight the distinct phenomenology in altermagnets of this time-reversal symmetry breaking response, and its potential utility for element-specific spectroscopy and microscopy.
Collapse
Affiliation(s)
- A Hariki
- Department of Physics and Electronics, Graduate School of Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - A Dal Din
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - O J Amin
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - T Yamaguchi
- Department of Physics and Electronics, Graduate School of Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - A Badura
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
| | - D Kriegner
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
| | - K W Edmonds
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - R P Campion
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - P Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - D Backes
- Diamond Light Source, Chilton OX11 0DE, United Kingdom
| | - L S I Veiga
- Diamond Light Source, Chilton OX11 0DE, United Kingdom
| | - S S Dhesi
- Diamond Light Source, Chilton OX11 0DE, United Kingdom
| | - G Springholz
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstraße 69, 4040 Linz, Austria
| | - L Šmejkal
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - K Výborný
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
| | - T Jungwirth
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
| | - J Kuneš
- Institute for Solid State Physics, TU Wien, 1040 Vienna, Austria
- Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czechia
| |
Collapse
|
2
|
Yan J, Ye K, Jia Z, Zhang Z, Li P, Liu L, Mu C, Huang H, Cheng Y, Nie A, Xiang J, Wang S, Liu Z. High-Performance Broadband Image Sensing Photodetector Based on MnTe/WS 2 van der Waals Epitaxial Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2024; 16:19112-19120. [PMID: 38579811 DOI: 10.1021/acsami.4c00159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/07/2024]
Abstract
Two-dimensional transition metal dichalcogenide (TMDC) heterostructure is receiving considerable attention due to its novel electronic, optoelectronic, and spintronic devices with design-oriented and functional features. However, direct design and synthesis of high-quality TMDC/MnTe heterostructures remain difficult, which severely impede further investigations of semiconductor/magnetic semiconductor devices. Herein, the synthesis of high-quality vertically stacked WS2/MnTe heterostructures is realized via a two-step chemical vapor deposition method. Raman, photoluminescence, and scanning transmission electron microscopy characterizations reveal the high-quality and atomically sharp interfaces of the WS2/MnTe heterostructure. WS2/MnTe-based van der Waals field effect transistors demonstrate high rectification behavior with rectification ratio up to 106, as well as a typical p-n electrical transport characteristic. Notably, the fabricated WS2/MnTe photodetector exhibits sensitive and broadband photoresponse ranging from UV to NIR with a maximum responsivity of 1.2 × 103 A/W, a high external quantum efficiency of 2.7 × 105%, and fast photoresponse time of ∼50 ms. Moreover, WS2/MnTe heterostructure photodetectors possess a broadband image sensing capability at room temperature, suggesting potential applications in next-generation high-performance and broadband image sensing photodetectors.
Collapse
Affiliation(s)
- Junxin Yan
- Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
| | - Kun Ye
- Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei 230601, China
- Institute of Quantum Materials and Devices, School of Electronics and Information Engineering, Tiangong University, Tianjin 300387, China
| | - Zhiyan Jia
- Institute of Quantum Materials and Devices, School of Electronics and Information Engineering, Tiangong University, Tianjin 300387, China
| | - Zeyu Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Penghui Li
- Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
| | - Lixuan Liu
- Institute of Quantum Materials and Devices, School of Electronics and Information Engineering, Tiangong University, Tianjin 300387, China
| | - Congpu Mu
- Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
| | - He Huang
- Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yingchun Cheng
- Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
| | - Anmin Nie
- Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
| | - Jianyong Xiang
- Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
| | - Shouguo Wang
- Anhui Key Laboratory of Magnetic Functional Materials and Devices, School of Materials Science and Engineering, Anhui University, Hefei 230601, China
| | - Zhongyuan Liu
- Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
| |
Collapse
|
3
|
Hajlaoui M, Wilfred D'Souza S, Šmejkal L, Kriegner D, Krizman G, Zakusylo T, Olszowska N, Caha O, Michalička J, Sánchez-Barriga J, Marmodoro A, Výborný K, Ernst A, Cinchetti M, Minar J, Jungwirth T, Springholz G. Temperature Dependence of Relativistic Valence Band Splitting Induced by an Altermagnetic Phase Transition. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2314076. [PMID: 38619144 DOI: 10.1002/adma.202314076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/07/2024] [Indexed: 04/16/2024]
Abstract
Altermagnetic (AM) materials exhibit non-relativistic, momentum-dependent spin-split states, ushering in new opportunities for spin electronic devices. While the characteristics of spin-splitting are documented within the framework of the non-relativistic spin group symmetry, there is limited exploration of the inclusion of relativistic symmetry and its impact on the emergence of a novel spin-splitting in the band structure. This study delves into the intricate relativistic electronic structure of an AM material, α-MnTe. Employing temperature-dependent angle-resolved photoelectron spectroscopy across the AM phase transition, the emergence of a relativistic valence band splitting concurrent with the establishment of magnetic order is elucidated. This discovery is validated through disordered local moment calculations, modeling the influence of magnetic order on the electronic structure and confirming the magnetic origin of the observed splitting. The temperature-dependent splitting is ascribed to the advent of relativistic spin-splitting resulting from the strengthening of AM order in α-MnTe as the temperature decreases. This sheds light on a previously unexplored facet of this intriguing material.
Collapse
Affiliation(s)
- Mahdi Hajlaoui
- Institute of Semiconductors and Solid-State Physics, Johannes Kepler University, Linz, 4040, Austria
| | - Sunil Wilfred D'Souza
- University of West Bohemia, New Technologies Research Center, Pilsen, 30100, Czech Republic
| | - Libor Šmejkal
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Praha, 16200, Czech Republic
- Institute of Physics, Johannes Gutenberg University Mainz, D-55099, Mainz, Germany
| | - Dominik Kriegner
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Praha, 16200, Czech Republic
| | - Gauthier Krizman
- Institute of Semiconductors and Solid-State Physics, Johannes Kepler University, Linz, 4040, Austria
| | - Tetiana Zakusylo
- Institute of Semiconductors and Solid-State Physics, Johannes Kepler University, Linz, 4040, Austria
| | - Natalia Olszowska
- National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, Czerwone Maki 98, Krakow, 30-392, Poland
| | - Ondřej Caha
- Department of Condensed Matter Physics, Masaryk University, Kotlářská 267/2, Brno, 61137, Czech Republic
| | - Jan Michalička
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, Brno, 61200, Czech Republic
| | - Jaime Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489, Berlin, Germany
- IMDEA Nanoscience, C/Faraday 9, Campus de Cantoblanco, Madrid, 28049, Spain
| | - Alberto Marmodoro
- University of West Bohemia, New Technologies Research Center, Pilsen, 30100, Czech Republic
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Praha, 16200, Czech Republic
| | - Karel Výborný
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Praha, 16200, Czech Republic
| | - Arthur Ernst
- Institute for Theoretical Physics, Johannes Kepler University, Linz, 4040, Austria
| | - Mirko Cinchetti
- Department of Physics, TU Dortmund University, 44227, Dortmund, Germany
| | - Jan Minar
- University of West Bohemia, New Technologies Research Center, Pilsen, 30100, Czech Republic
| | - Tomas Jungwirth
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Praha, 16200, Czech Republic
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Gunther Springholz
- Institute of Semiconductors and Solid-State Physics, Johannes Kepler University, Linz, 4040, Austria
| |
Collapse
|
4
|
Krempaský J, Šmejkal L, D'Souza SW, Hajlaoui M, Springholz G, Uhlířová K, Alarab F, Constantinou PC, Strocov V, Usanov D, Pudelko WR, González-Hernández R, Birk Hellenes A, Jansa Z, Reichlová H, Šobáň Z, Gonzalez Betancourt RD, Wadley P, Sinova J, Kriegner D, Minár J, Dil JH, Jungwirth T. Altermagnetic lifting of Kramers spin degeneracy. Nature 2024; 626:517-522. [PMID: 38356066 PMCID: PMC10866710 DOI: 10.1038/s41586-023-06907-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/28/2023] [Indexed: 02/16/2024]
Abstract
Lifted Kramers spin degeneracy (LKSD) has been among the central topics of condensed-matter physics since the dawn of the band theory of solids1,2. It underpins established practical applications as well as current frontier research, ranging from magnetic-memory technology3-7 to topological quantum matter8-14. Traditionally, LKSD has been considered to originate from two possible internal symmetry-breaking mechanisms. The first refers to time-reversal symmetry breaking by magnetization of ferromagnets and tends to be strong because of the non-relativistic exchange origin15. The second applies to crystals with broken inversion symmetry and tends to be comparatively weaker, as it originates from the relativistic spin-orbit coupling (SOC)16-19. A recent theory work based on spin-symmetry classification has identified an unconventional magnetic phase, dubbed altermagnetic20,21, that allows for LKSD without net magnetization and inversion-symmetry breaking. Here we provide the confirmation using photoemission spectroscopy and ab initio calculations. We identify two distinct unconventional mechanisms of LKSD generated by the altermagnetic phase of centrosymmetric MnTe with vanishing net magnetization20-23. Our observation of the altermagnetic LKSD can have broad consequences in magnetism. It motivates exploration and exploitation of the unconventional nature of this magnetic phase in an extended family of materials, ranging from insulators and semiconductors to metals and superconductors20,21, that have been either identified recently or perceived for many decades as conventional antiferromagnets21,24,25.
Collapse
Affiliation(s)
- J Krempaský
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland.
| | - L Šmejkal
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - S W D'Souza
- New Technologies Research Center, University of West Bohemia, Plzeň, Czech Republic
| | - M Hajlaoui
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University of Linz, Linz, Austria
| | - G Springholz
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University of Linz, Linz, Austria
| | - K Uhlířová
- Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - F Alarab
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
| | - P C Constantinou
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
| | - V Strocov
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
| | - D Usanov
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
| | - W R Pudelko
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
- Physik-Institut, Universität Zürich, Zürich, Switzerland
| | - R González-Hernández
- Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla, Colombia
| | - A Birk Hellenes
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Z Jansa
- New Technologies Research Center, University of West Bohemia, Plzeň, Czech Republic
| | - H Reichlová
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - Z Šobáň
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | | | - P Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom
| | - J Sinova
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - D Kriegner
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - J Minár
- New Technologies Research Center, University of West Bohemia, Plzeň, Czech Republic.
| | - J H Dil
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
- Institut de Physique, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - T Jungwirth
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic.
- School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom.
| |
Collapse
|
5
|
Deng S, Gomonay O, Chen J, Fischer G, He L, Wang C, Huang Q, Shen F, Tan Z, Zhou R, Hu Z, Šmejkal L, Sinova J, Wernsdorfer W, Sürgers C. Phase transitions associated with magnetic-field induced topological orbital momenta in a non-collinear antiferromagnet. Nat Commun 2024; 15:822. [PMID: 38280875 PMCID: PMC10821865 DOI: 10.1038/s41467-024-45129-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 01/11/2024] [Indexed: 01/29/2024] Open
Abstract
Resistivity measurements are widely exploited to uncover electronic excitations and phase transitions in metallic solids. While single crystals are preferably studied to explore crystalline anisotropies, these usually cancel out in polycrystalline materials. Here we show that in polycrystalline Mn3Zn0.5Ge0.5N with non-collinear antiferromagnetic order, changes in the diagonal and, rather unexpected, off-diagonal components of the resistivity tensor occur at low temperatures indicating subtle transitions between magnetic phases of different symmetry. This is supported by neutron scattering and explained within a phenomenological model which suggests that the phase transitions in magnetic field are associated with field induced topological orbital momenta. The fact that we observe transitions between spin phases in a polycrystal, where effects of crystalline anisotropy are cancelled suggests that they are only controlled by exchange interactions. The observation of an off-diagonal resistivity extends the possibilities for realising antiferromagnetic spintronics with polycrystalline materials.
Collapse
Affiliation(s)
- Sihao Deng
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, 76049, Germany.
- Spallation Neutron Source Science Center, Dongguan, 523803, China.
| | - Olena Gomonay
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55128, Mainz, Germany
| | - Jie Chen
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- Spallation Neutron Source Science Center, Dongguan, 523803, China
| | - Gerda Fischer
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, 76049, Germany
| | - Lunhua He
- Spallation Neutron Source Science Center, Dongguan, 523803, China.
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- Songshan Lake Materials Laboratory, Dongguan, 523808, China.
| | - Cong Wang
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
| | - Qingzhen Huang
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Feiran Shen
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- Spallation Neutron Source Science Center, Dongguan, 523803, China
| | - Zhijian Tan
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- Spallation Neutron Source Science Center, Dongguan, 523803, China
| | - Rui Zhou
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Ze Hu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Renmin University of China, Beijing, 100872, China
| | - Libor Šmejkal
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55128, Mainz, Germany
| | - Jairo Sinova
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55128, Mainz, Germany
| | - Wolfgang Wernsdorfer
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, 76049, Germany
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, Karlsruhe, 76021, Germany
| | - Christoph Sürgers
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, 76049, Germany.
| |
Collapse
|
6
|
Lee S, Lee S, Jung S, Jung J, Kim D, Lee Y, Seok B, Kim J, Park BG, Šmejkal L, Kang CJ, Kim C. Broken Kramers Degeneracy in Altermagnetic MnTe. PHYSICAL REVIEW LETTERS 2024; 132:036702. [PMID: 38307068 DOI: 10.1103/physrevlett.132.036702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/14/2023] [Indexed: 02/04/2024]
Abstract
Altermagnetism is a newly identified fundamental class of magnetism with vanishing net magnetization and time-reversal symmetry broken electronic structure. Probing the unusual electronic structure with nonrelativistic spin splitting would be a direct experimental verification of an altermagnetic phase. By combining high-quality film growth and in situ angle-resolved photoemission spectroscopy, we report the electronic structure of an altermagnetic candidate, α-MnTe. Temperature-dependent study reveals the lifting of Kramers degeneracy accompanied by a magnetic phase transition at T_{N}=267 K with spin splitting of up to 370 meV, providing direct spectroscopic evidence for altermagnetism in MnTe.
Collapse
Affiliation(s)
- Suyoung Lee
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Sangjae Lee
- The Research Institute of Basic Sciences, Seoul National University, Seoul 08826, Korea
| | - Saegyeol Jung
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Jiwon Jung
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Donghan Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Yeonjae Lee
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Byeongjun Seok
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Jaeyoung Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Byeong Gyu Park
- Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Libor Šmejkal
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - Chang-Jong Kang
- Department of Physics, Chungnam National University, Daejeon 34134, Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| |
Collapse
|
7
|
Ritzinger P, Výborný K. Anisotropic magnetoresistance: materials, models and applications. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230564. [PMID: 37859834 PMCID: PMC10582618 DOI: 10.1098/rsos.230564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 09/07/2023] [Indexed: 10/21/2023]
Abstract
Resistance of certain (conductive and otherwise isotropic) ferromagnets turns out to exhibit anisotropy with respect to the direction of magnetization: R ∥ for magnetization parallel to the electric current direction is different from R⊥ for magnetization perpendicular to the electric current direction. In this review, this century-old phenomenon is reviewed both from the perspective of materials and physical mechanisms involved. More recently, this effect has also been identified and studied in antiferromagnets. To date, sensors based on the anisotropic magnetoresistance (AMR) effect are widely used in different fields, such as the automotive industry, aerospace or in biomedical imaging.
Collapse
Affiliation(s)
- Philipp Ritzinger
- FZU—Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, Praha 6 16253, Czech Republic
- MFF—Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, Praha 2 12000, Czech Republic
| | - Karel Výborný
- FZU—Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, Praha 6 16253, Czech Republic
| |
Collapse
|
8
|
Kalal S, Nayak S, Sahoo S, Joshi R, Choudhary RJ, Rawat R, Gupta M. Electronic correlations in epitaxial CrN thin film. Sci Rep 2023; 13:15994. [PMID: 37749139 PMCID: PMC10519984 DOI: 10.1038/s41598-023-42733-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 09/14/2023] [Indexed: 09/27/2023] Open
Abstract
Chromium nitride (CrN) spurred enormous interest due to its coupled magnetostructural and unique metal-insulator transition. The underneath electronic structure of CrN remains elusive. Herein, the electronic structure of epitaxial CrN thin film has been explored by employing resonant photoemission spectroscopy (RPES) and X-ray absorption near edge spectroscopy study in combination with the first-principles calculations. The RPES study indicates the presence of a charge-transfer screened 3[Formula: see text] ([Formula: see text]: hole in the N-2[Formula: see text]) and 3[Formula: see text] final-states in the valence band regime. The combined experimental electronic structure along with the orbital resolved electronic density of states from the first-principles calculations reveals the presence of Cr(3[Formula: see text])-N(2[Formula: see text]) hybridized (3[Formula: see text]) states between lower Hubbard (3[Formula: see text]) and upper Hubbard (3[Formula: see text]) bands with onsite Coulomb repulsion energy (U) and charge-transfer energy ([Formula: see text]) estimated as [Formula: see text] 4.5 and 3.6 eV, respectively. It verifies the participation of ligand (N-2[Formula: see text]) states in low energy charge fluctuations and provides concrete evidence for the charge-transfer ([Formula: see text]U) insulating nature of CrN thin film.
Collapse
Affiliation(s)
- Shailesh Kalal
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore, 452 001, India
| | - Sanjay Nayak
- Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83, Linköping, Sweden
| | - Sophia Sahoo
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore, 452 001, India
| | - Rajeev Joshi
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore, 452 001, India
| | - Ram Janay Choudhary
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore, 452 001, India
| | - Rajeev Rawat
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore, 452 001, India
| | - Mukul Gupta
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore, 452 001, India.
| |
Collapse
|
9
|
Fang M, Yang EH. Advances in Two-Dimensional Magnetic Semiconductors via Substitutional Doping of Transition Metal Dichalcogenides. MATERIALS (BASEL, SWITZERLAND) 2023; 16:ma16103701. [PMID: 37241328 DOI: 10.3390/ma16103701] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/14/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023]
Abstract
Transition metal dichalcogenides (TMDs) are two-dimensional (2D) materials with remarkable electrical, optical, and chemical properties. One promising strategy to tailor the properties of TMDs is to create alloys through a dopant-induced modification. Dopants can introduce additional states within the bandgap of TMDs, leading to changes in their optical, electronic, and magnetic properties. This paper overviews chemical vapor deposition (CVD) methods to introduce dopants into TMD monolayers, and discusses the advantages, limitations, and their impacts on the structural, electrical, optical, and magnetic properties of substitutionally doped TMDs. The dopants in TMDs modify the density and type of carriers in the material, thereby influencing the optical properties of the materials. The magnetic moment and circular dichroism in magnetic TMDs are also strongly affected by doping, which enhances the magnetic signal in the material. Finally, we highlight the different doping-induced magnetic properties of TMDs, including superexchange-induced ferromagnetism and valley Zeeman shift. Overall, this review paper provides a comprehensive summary of magnetic TMDs synthesized via CVD, which can guide future research on doped TMDs for various applications, such as spintronics, optoelectronics, and magnetic memory devices.
Collapse
Affiliation(s)
- Mengqi Fang
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Eui-Hyeok Yang
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
- Center for Quantum Science and Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| |
Collapse
|
10
|
Spin-flip-driven anomalous Hall effect and anisotropic magnetoresistance in a layered Ising antiferromagnet. Sci Rep 2023; 13:3391. [PMID: 36854958 PMCID: PMC9974960 DOI: 10.1038/s41598-023-30076-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 02/15/2023] [Indexed: 03/02/2023] Open
Abstract
The influence of magnetocrystalline anisotropy in antiferromagnets is evident in a spin flip or flop transition. Contrary to spin flops, a spin-flip transition has been scarcely presented due to its specific condition of relatively strong magnetocrystalline anisotropy and the role of spin-flips on anisotropic phenomena has not been investigated in detail. In this study, we present antiferromagnet-based functional properties on an itinerant Ising antiferromagnet Ca0.9Sr0.1Co2As2. In the presence of a rotating magnetic field, anomalous Hall conductivity and anisotropic magnetoresistance are demonstrated, the effects of which are maximized above the spin-flip transition. Moreover, a joint experimental and theoretical study is conducted to provide an efficient tool to identify various spin states, which can be useful in spin-processing functionalities.
Collapse
|
11
|
Han J, Lv C, Yang W, Wang X, Wei G, Zhao W, Lin X. Large tunneling magnetoresistance in van der Waals magnetic tunnel junctions based on FeCl 2 films with interlayer antiferromagnetic couplings. NANOSCALE 2023; 15:2067-2078. [PMID: 36594492 DOI: 10.1039/d2nr05684d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Antiferromagnets (AFMs) are some of the most promising candidates for next-generation magnetic memory technology owing to their advantages over conventional ferromagnets (FMs), such as zero stray field and THz-range magnetic resonance frequency. Motivated by the recent synthesis of FeCl2 films with interlayer AFM and intralayer FM couplings, we investigated the magnetic properties of few-layer FeCl2 and the spin-dependent transmissions of graphite/bilayer FeCl2/graphite and Au/n-layer FeCl2/Au magnetic tunnel junctions (MTJs) using first-principles calculations combined with the nonequilibrium Green's function. The interlayer AFM coupling of FeCl2 is certified to be stable and independent of the stacking orders and relative displacement between layers. Furthermore, based on the Au electrode with better conductive performance than the graphite electrode and monolayer 1T-FeCl2 with complete spin polarization, high Curie temperature and large magnetic anisotropic energy, a high tunnel magnetoresistance (TMR) ratio of 2.7 × 103% is achieved in Au/bilayer FeCl2/Au MTJs at zero bias and it increases with different layers of FeCl2 (n = 2-10). These excellent spin transport properties of Au/n-layer FeCl2/Au MTJs based on two-dimensional (2D) AFM barriers with out-of-plane magnetization directions suggest their great potential for application in high-reliability, high-speed and high-density spintronic devices.
Collapse
Affiliation(s)
- Jiangchao Han
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China.
| | - Chen Lv
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China.
| | - Wei Yang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China.
| | - Xinhe Wang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China.
| | - Guodong Wei
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China.
| | - Weisheng Zhao
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China.
| | - Xiaoyang Lin
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China.
| |
Collapse
|
12
|
Gonzalez Betancourt RD, Zubáč J, Gonzalez-Hernandez R, Geishendorf K, Šobáň Z, Springholz G, Olejník K, Šmejkal L, Sinova J, Jungwirth T, Goennenwein STB, Thomas A, Reichlová H, Železný J, Kriegner D. Spontaneous Anomalous Hall Effect Arising from an Unconventional Compensated Magnetic Phase in a Semiconductor. PHYSICAL REVIEW LETTERS 2023; 130:036702. [PMID: 36763381 DOI: 10.1103/physrevlett.130.036702] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 10/10/2022] [Accepted: 12/21/2022] [Indexed: 06/18/2023]
Abstract
The anomalous Hall effect, commonly observed in metallic magnets, has been established to originate from the time-reversal symmetry breaking by an internal macroscopic magnetization in ferromagnets or by a noncollinear magnetic order. Here we observe a spontaneous anomalous Hall signal in the absence of an external magnetic field in an epitaxial film of MnTe, which is a semiconductor with a collinear antiparallel magnetic ordering of Mn moments and a vanishing net magnetization. The anomalous Hall effect arises from an unconventional phase with strong time-reversal symmetry breaking and alternating spin polarization in real-space crystal structure and momentum-space electronic structure. The anisotropic crystal environment of magnetic Mn atoms due to the nonmagnetic Te atoms is essential for establishing the unconventional phase and generating the anomalous Hall effect.
Collapse
Affiliation(s)
- R D Gonzalez Betancourt
- Institute of Solid State and Materials Physics, Technical University Dresden, 01062 Dresden, Germany
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- Leibniz Institute of Solid State and Materials Research (IFW Dresden), Helmholtzstr. 20, 01069 Dresden, Germany
| | - J Zubáč
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
| | - R Gonzalez-Hernandez
- Departamento de Fisica y Geociencias, Universidad del Norte, Barranquilla 080020, Colombia
| | - K Geishendorf
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - Z Šobáň
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - G Springholz
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - K Olejník
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - L Šmejkal
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55128 Mainz, Germany
| | - J Sinova
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55128 Mainz, Germany
| | - T Jungwirth
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - S T B Goennenwein
- Institute of Solid State and Materials Physics, Technical University Dresden, 01062 Dresden, Germany
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | - A Thomas
- Institute of Solid State and Materials Physics, Technical University Dresden, 01062 Dresden, Germany
- Leibniz Institute of Solid State and Materials Research (IFW Dresden), Helmholtzstr. 20, 01069 Dresden, Germany
| | - H Reichlová
- Institute of Solid State and Materials Physics, Technical University Dresden, 01062 Dresden, Germany
| | - J Železný
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - D Kriegner
- Institute of Solid State and Materials Physics, Technical University Dresden, 01062 Dresden, Germany
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| |
Collapse
|
13
|
Ding S, Chen C, Cao Z, Wang D, Pan Y, Tao R, Zhao D, Hu Y, Jiang T, Yan Y, Shi Z, Wan X, Feng D, Zhang T. Observation of robust zero-energy state and enhanced superconducting gap in a trilayer heterostructure of MnTe/Bi 2Te 3/Fe(Te, Se). SCIENCE ADVANCES 2022; 8:eabq4578. [PMID: 36103530 PMCID: PMC9473575 DOI: 10.1126/sciadv.abq4578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 07/28/2022] [Indexed: 06/15/2023]
Abstract
The interface between magnetic material and superconductors has long been predicted to host unconventional superconductivity, such as spin-triplet pairing and topological nontrivial pairing state, particularly when spin-orbital coupling (SOC) is incorporated. To identify these unconventional pairing states, fabricating homogenous heterostructures that contain such various properties are preferred but often challenging. Here, we synthesized a trilayer-type van der Waals heterostructure of MnTe/Bi2Te3/Fe(Te, Se), which combined s-wave superconductivity, thickness-dependent magnetism, and strong SOC. Via low-temperature scanning tunneling microscopy, we observed robust zero-energy states with notably nontrivial properties and an enhanced superconducting gap size on single unit cell (UC) MnTe surface. In contrast, no zero-energy state was observed on 2-UC MnTe. First-principle calculations further suggest that the 1-UC MnTe has large interfacial Dzyaloshinskii-Moriya interaction and a frustrated AFM state, which could promote noncolinear spin textures. It thus provides a promising platform for exploring topological nontrivial superconductivity.
Collapse
Affiliation(s)
- Shuyue Ding
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai 200438, China
| | - Chen Chen
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai 200438, China
| | - Zhipeng Cao
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
| | - Di Wang
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
| | - Yongqiang Pan
- School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China
| | - Ran Tao
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai 200438, China
| | - Dongming Zhao
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai 200438, China
| | - Yining Hu
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai 200438, China
| | - Tianxing Jiang
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai 200438, China
| | - Yajun Yan
- Department of Physics, University of Science and Technology of China, Hefei 230026, China
| | - Zhixiang Shi
- School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China
| | - Xiangang Wan
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Donglai Feng
- Department of Physics, University of Science and Technology of China, Hefei 230026, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China
| | - Tong Zhang
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai 200438, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| |
Collapse
|
14
|
Autieri C, Cuono G, Noce C, Rybak M, Kotur KM, Agrapidis CE, Wohlfeld K, Birowska M. Limited Ferromagnetic Interactions in Monolayers of MPS 3 (M = Mn and Ni). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:6791-6802. [PMID: 35493696 PMCID: PMC9037203 DOI: 10.1021/acs.jpcc.2c00646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/30/2022] [Indexed: 06/14/2023]
Abstract
We present a systematic study of the electronic and magnetic properties of two-dimensional ordered alloys, consisting of two representative hosts (MnPS3 and NiPS3) of transition metal phosphorus trichalcogenides doped with 3d elements. For both hosts, our DFT + U calculations are able to qualitatively reproduce the ratios and signs of all experimentally observed magnetic couplings. The relative strength of all antiferromagnetic exchange couplings, both in MnPS3 and in NiPS3, can successfully be explained using an effective direct exchange model: it reveals that the third-neighbor exchange dominates in NiPS3 due to the filling of the t2g subshell, whereas for MnPS3, the first-neighbor exchange prevails, owing to the presence of the t2g magnetism. On the other hand, the nearest neighbor ferromagnetic coupling in NiPS3 can only be explained using a more complex superexchange model and is (also) largely triggered by the absence of the t2g magnetism. For the doped systems, the DFT + U calculations revealed that magnetic impurities do not affect the magnetic ordering observed in the pure phases, and thus, in general in these systems, ferromagnetism may not be easily induced by such a kind of elemental doping. However, unlike for the hosts, the first and second (dopant-host) exchange couplings are of similar order of magnitude. This leads to frustration in the case of antiferromagnetic coupling and may be one of the reasons of the observed lower magnetic ordering temperature of the doped systems.
Collapse
Affiliation(s)
- Carmine Autieri
- International
Research Centre Magtop, Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, PL-02668 Warsaw, Poland
- Consiglio
Nazionale delle Ricerche CNR-SPIN, UOS Salerno, I-84084 Fisciano, Salerno, Italy
| | - Giuseppe Cuono
- International
Research Centre Magtop, Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, PL-02668 Warsaw, Poland
| | - Canio Noce
- Dipartimento
di Fisica “E.R. Caianiello”, Università degli Studi di Salerno, I-84084 Fisciano, Salerno, Italy
- Consiglio
Nazionale delle Ricerche CNR-SPIN, UOS Salerno, I-84084 Fisciano, Salerno, Italy
| | - Milosz Rybak
- Department
of Semiconductor Materials Engineering, Faculty of Fundamental Problems
of Technology, Wrocław University
of Science and Technology, Wybrzeże Wyspiańskiego 27, PL-50370 Wrocław, Poland
| | - Kamila M. Kotur
- Faculty
of Physics, University of Warsaw, Pasteura 5, PL-02093 Warsaw, Poland
| | | | - Krzysztof Wohlfeld
- Faculty
of Physics, University of Warsaw, Pasteura 5, PL-02093 Warsaw, Poland
| | - Magdalena Birowska
- Faculty
of Physics, University of Warsaw, Pasteura 5, PL-02093 Warsaw, Poland
| |
Collapse
|
15
|
Xu J, Xia J, Zhang X, Zhou C, Shi D, Chen H, Wu T, Li Q, Ding H, Zhou Y, Wu Y. Exchange-Torque-Triggered Fast Switching of Antiferromagnetic Domains. PHYSICAL REVIEW LETTERS 2022; 128:137201. [PMID: 35426702 DOI: 10.1103/physrevlett.128.137201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/27/2022] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
The antiferromagnet is considered to be a promising hosting material for the next generation of magnetic storage due to its high stability and stray-field-free property. Understanding the switching properties of the antiferromagnetic (AFM) domain state is critical for developing AFM spintronics. By utilizing the magneto-optical birefringence effect, we experimentally demonstrate the switching rate of the AFM domain can be enhanced by more than 2 orders of magnitude through applying an alternating square-wave field on a single crystalline Fe/CoO bilayer. The observed extraordinary speed can be much faster than that triggered by a constant field with the same amplitude. The effect can be understood as the efficient suppression of the pinning of AFM domain walls by the strong exchange torque triggered by the reversal of the Fe magnetization, as revealed by spin dynamics simulations. Our finding opens up new opportunities to design the antiferromagnet-based spintronic devices utilizing the ferromagnet-antiferromagnet heterostructure.
Collapse
Affiliation(s)
- Jia Xu
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
- Institute of Physics, Shaanxi University of Technology, Hanzhong 723001, China
| | - Jing Xia
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
- College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068, China
| | - Xichao Zhang
- Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
| | - Chao Zhou
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
- Institute of Physics, Shaanxi University of Technology, Hanzhong 723001, China
| | - Dong Shi
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
| | - Haoran Chen
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
| | - Tong Wu
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
| | - Qian Li
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
| | - Haifeng Ding
- National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, China
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Yizheng Wu
- Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| |
Collapse
|
16
|
Wu Y, Wang W, Pan L, Wang KL. Manipulating Exchange Bias in a Van der Waals Ferromagnet. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2105266. [PMID: 34910836 DOI: 10.1002/adma.202105266] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 12/01/2021] [Indexed: 06/14/2023]
Abstract
Spintronics applications of thin-film magnets require control and design of specific magnetic properties. Exchange bias, originating from the pinning of spins in a ferromagnet by these of an antiferromagnet, is a part of the highly important elements for spintronics applications. Here, an exchange bias of ≈90 mT in a van der Waals ferromagnet encapsulated by two antiferromagnets at 5 K, the value of which is highly tunable by the field coolings, is reported. The non-antisymmetric dependence of exchange bias on field cooling is explained through considering an uncompensated interfacial magnetic layer of an antiferromagnet with a noncollinear spin texture, and a weak antiferromagnetic order in the oxidized layer, at two ferromagnet/antiferromagnet interfaces. This work opens up new routes toward designing and controlling 2D spintronic devices made of atomically thin van der Waals magnets.
Collapse
Affiliation(s)
- Yingying Wu
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Wei Wang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China
| | - Lei Pan
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| |
Collapse
|
17
|
Visualizing rotation and reversal of the Néel vector through antiferromagnetic trichroism. Nat Commun 2022; 13:697. [PMID: 35121748 PMCID: PMC8816959 DOI: 10.1038/s41467-022-28215-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 01/10/2022] [Indexed: 11/10/2022] Open
Abstract
Conventional magnetic memories rely on bistable magnetic states, such as the up and down magnetization states in ferromagnets. Increasing the number of stable magnetic states in each cell, preferably composed of antiferromagnets without stray fields, promises to achieve higher-capacity memories. Thus far, such multi-stable antiferromagnetic states have been extensively studied in conducting systems. Here, we report on a striking optical response in the magnetoelectric collinear antiferromagnet Bi2CuO4, which is an insulating version of the representative spintronic material, CuMnAs, with four stable Néel vector orientations. We find that, due to a magnetoelectric effect in a visible range, which is enhanced by a peculiar local environment of Cu ions, absorption coefficient takes three discrete values depending on an angle between the propagation vector of light and the Néel vector—a phenomenon that we term antiferromagnetic trichroism. Furthermore, using this antiferromagnetic trichroism, we successfully visualize field-driven reversal and rotation of the Néel vector. Antiferromagnets have great promise for use in spin-based electronics; however, detecting the Neel vector is challenging due to the lack of a net magnetization. Here, Kimura et al demonstrate an intriguing optical response, where the optical absorption depends on the angle of the Neel vector.
Collapse
|
18
|
Su SH, Chang JT, Chuang PY, Tsai MC, Peng YW, Lee MK, Cheng CM, Huang JCA. Epitaxial Growth and Structural Characterizations of MnBi 2Te 4 Thin Films in Nanoscale. NANOMATERIALS 2021; 11:nano11123322. [PMID: 34947669 PMCID: PMC8703544 DOI: 10.3390/nano11123322] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/02/2021] [Accepted: 12/02/2021] [Indexed: 11/30/2022]
Abstract
The intrinsic magnetic topological insulator MnBi2Te4 has attracted much attention due to its special magnetic and topological properties. To date, most reports have focused on bulk or flake samples. For material integration and device applications, the epitaxial growth of MnBi2Te4 film in nanoscale is more important but challenging. Here, we report the growth of self-regulated MnBi2Te4 films by the molecular beam epitaxy. By tuning the substrate temperature to the optimal temperature for the growth surface, the stoichiometry of MnBi2Te4 becomes sensitive to the Mn/Bi flux ratio. Excessive and deficient Mn resulted in the formation of a MnTe and Bi2Te3 phase, respectively. The magnetic measurement of the 7 SL MnBi2Te4 film probed by the superconducting quantum interference device (SQUID) shows that the antiferromagnetic order occurring at the Néel temperature 22 K is accompanied by an anomalous magnetic hysteresis loop along the c-axis. The band structure measured by angle-resolved photoemission spectroscopy (ARPES) at 80 K reveals a Dirac-like surface state, which indicates that MnBi2Te4 has topological insulator properties in the paramagnetic phase. Our work demonstrates the key growth parameters for the design and optimization of the synthesis of nanoscale MnBi2Te4 films, which are of great significance for fundamental research and device applications involving antiferromagnetic topological insulators.
Collapse
Affiliation(s)
- Shu-Hsuan Su
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Jen-Te Chang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Pei-Yu Chuang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Ming-Chieh Tsai
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Yu-Wei Peng
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Min Kai Lee
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
| | - Cheng-Maw Cheng
- National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
- Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106335, Taiwan
- Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan
- Correspondence: (C.-M.C.); (J.-C.A.H.)
| | - Jung-Chung Andrew Huang
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan; (S.-H.S.); (J.-T.C.); (P.-Y.C.); (M.-C.T.); (Y.-W.P.); (M.K.L.)
- Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan
- Department of Applied Physics, National University of Kaohsiung, Kaohsiung, 811, Taiwan
- Correspondence: (C.-M.C.); (J.-C.A.H.)
| |
Collapse
|
19
|
Wang F, Yang H, Zhang H, Zhou J, Wang J, Hu L, Xue DJ, Xu X. One-Pot Synthesis Enables Magnetic Coupled Cr 2Te 3/MnTe/Cr 2Te 3 Integrated Heterojunction Nanorods. NANO LETTERS 2021; 21:7684-7690. [PMID: 34435772 DOI: 10.1021/acs.nanolett.1c02481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Magnetic heterostructures offer great promise in spintronic devices due to their unique magnetic properties, such as exchange bias effect, topological superconductivity, and magneto-resistance. Although various magnetic heterostructures including core/shell, multilayer, and van der Waals systems have been fabricated recently, the construction of perfect heterointerfaces usually rely on complicated and high-cost fabrication methods such as molecular-beam epitaxy; surprisingly, few one-dimensional (1D) bimagnetic heterojunctions, which provide multidegrees of freedom to modulate magnetic properties via magnetic anisotropy and interface coupling, have been fabricated to date. Here we report a one-pot solution-based method for the synthesis of ferromagnetic/antiferromagnetic/ferromagnetic heterojunction nanorods with excellent heterointerfaces in the case of Cr2Te3/MnTe/Cr2Te3. The precise control of homogeneous nucleation of MnTe and heterogeneous nucleation of Cr2Te3 is a key factor in synthesizing this heterostructure. The resulting 1D bimagnetic heterojunction nanorods exhibit high coercivity of 5.8 kOe and exchange bias of 892.5 Oe achieved by the magnetic MnTe/Cr2Te3 interface coupling.
Collapse
Affiliation(s)
- Fang Wang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, China
| | - Huan Yang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, China
| | - Huisheng Zhang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, China
| | - Jie Zhou
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, China
| | - Juanjuan Wang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, China
| | - Liyan Hu
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, China
| | - Ding-Jiang Xue
- Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaohong Xu
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, China
| |
Collapse
|
20
|
Wang X, Cao J, Lu Z, Cohen A, Kitadai H, Li T, Tan Q, Wilson M, Lui CH, Smirnov D, Sharifzadeh S, Ling X. Spin-induced linear polarization of photoluminescence in antiferromagnetic van der Waals crystals. NATURE MATERIALS 2021; 20:964-970. [PMID: 33903748 DOI: 10.1038/s41563-021-00968-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
Antiferromagnets are promising components for spintronics due to their terahertz resonance, multilevel states and absence of stray fields. However, the zero net magnetic moment of antiferromagnets makes the detection of the antiferromagnetic order and the investigation of fundamental spin properties notoriously difficult. Here, we report an optical detection of Néel vector orientation through an ultra-sharp photoluminescence in the van der Waals antiferromagnet NiPS3 from bulk to atomically thin flakes. The strong correlation between spin flipping and electric dipole oscillator results in a linear polarization of the sharp emission, which aligns perpendicular to the spin orientation in the crystal. By applying an in-plane magnetic field, we achieve manipulation of the photoluminescence polarization. This correlation between emitted photons and spins in layered magnets provides routes for investigating magneto-optics in two-dimensional materials, and hence opens a path for developing opto-spintronic devices and antiferromagnet-based quantum information technologies.
Collapse
Affiliation(s)
- Xingzhi Wang
- Department of Chemistry, Boston University, Boston, MA, USA.
| | - Jun Cao
- Department of Chemistry, Boston University, Boston, MA, USA
| | - Zhengguang Lu
- National High Magnetic Field Laboratory, Tallahassee, FL, USA
- Department of Physics, Florida State University, Tallahassee, FL, USA
| | - Arielle Cohen
- Division of Materials Science and Engineering, Boston University, Boston, MA, USA
| | - Hikari Kitadai
- Department of Chemistry, Boston University, Boston, MA, USA
| | - Tianshu Li
- Division of Materials Science and Engineering, Boston University, Boston, MA, USA
| | - Qishuo Tan
- Department of Chemistry, Boston University, Boston, MA, USA
| | - Matthew Wilson
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Chun Hung Lui
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Dmitry Smirnov
- National High Magnetic Field Laboratory, Tallahassee, FL, USA
| | - Sahar Sharifzadeh
- Department of Chemistry, Boston University, Boston, MA, USA
- Division of Materials Science and Engineering, Boston University, Boston, MA, USA
- Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
- Department of Physics, Boston University, Boston, MA, USA
| | - Xi Ling
- Department of Chemistry, Boston University, Boston, MA, USA.
- Division of Materials Science and Engineering, Boston University, Boston, MA, USA.
- The Photonics Center, Boston University, Boston, MA, USA.
| |
Collapse
|
21
|
Observation of current-induced switching in non-collinear antiferromagnetic IrMn 3 by differential voltage measurements. Nat Commun 2021; 12:3828. [PMID: 34158511 PMCID: PMC8219769 DOI: 10.1038/s41467-021-24237-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 06/09/2021] [Indexed: 11/19/2022] Open
Abstract
There is accelerating interest in developing memory devices using antiferromagnetic (AFM) materials, motivated by the possibility for electrically controlling AFM order via spin-orbit torques, and its read-out via magnetoresistive effects. Recent studies have shown, however, that high current densities create non-magnetic contributions to resistive switching signals in AFM/heavy metal (AFM/HM) bilayers, complicating their interpretation. Here we introduce an experimental protocol to unambiguously distinguish current-induced magnetic and nonmagnetic switching signals in AFM/HM structures, and demonstrate it in IrMn3/Pt devices. A six-terminal double-cross device is constructed, with an IrMn3 pillar placed on one cross. The differential voltage is measured between the two crosses with and without IrMn3 after each switching attempt. For a wide range of current densities, reversible switching is observed only when write currents pass through the cross with the IrMn3 pillar, eliminating any possibility of non-magnetic switching artifacts. Micromagnetic simulations support our findings, indicating a complex domain-mediated switching process. Anti-ferromagnetic based memories have a wide range of advantages over their ferromagnetic counterparts, however, their electrical signatures of switching are complicated by spurious signals. Here, Arpaci et al demonstrate an experimental method to distinguish between anti-ferromagnetic switching, and such spurious signatures.
Collapse
|
22
|
Seo J, An ES, Park T, Hwang SY, Kim GY, Song K, Noh WS, Kim JY, Choi GS, Choi M, Oh E, Watanabe K, Taniguchi T, Park JH, Jo YJ, Yeom HW, Choi SY, Shim JH, Kim JS. Tunable high-temperature itinerant antiferromagnetism in a van der Waals magnet. Nat Commun 2021; 12:2844. [PMID: 33990589 PMCID: PMC8121823 DOI: 10.1038/s41467-021-23122-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 04/13/2021] [Indexed: 11/29/2022] Open
Abstract
Discovery of two dimensional (2D) magnets, showing intrinsic ferromagnetic (FM) or antiferromagnetic (AFM) orders, has accelerated development of novel 2D spintronics, in which all the key components are made of van der Waals (vdW) materials and their heterostructures. High-performing and energy-efficient spin functionalities have been proposed, often relying on current-driven manipulation and detection of the spin states. In this regard, metallic vdW magnets are expected to have several advantages over the widely-studied insulating counterparts, but have not been much explored due to the lack of suitable materials. Here, we report tunable itinerant ferro- and antiferromagnetism in Co-doped Fe4GeTe2 utilizing the vdW interlayer coupling, extremely sensitive to the material composition. This leads to high TN antiferromagnetism of TN ~ 226 K in a bulk and ~210 K in 8 nm-thick nanoflakes, together with tunable magnetic anisotropy. The resulting spin configurations and orientations are sensitively controlled by doping, magnetic field, and thickness, which are effectively read out by electrical conduction. These findings manifest strong merits of metallic vdW magnets as an active component of vdW spintronic applications. Metallic van der Waals magnets have considerable technological promise, due to their ability to be strongly coupled with electronic currents and integrated in two dimensional heterostructures. Here, Seo et al. demonstrate highly tunable itinerant antiferromagnetism in a van der Waals magnet.
Collapse
Affiliation(s)
- Junho Seo
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, Korea.,Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Eun Su An
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, Korea.,Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Taesu Park
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Soo-Yoon Hwang
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Gi-Yeop Kim
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Kyung Song
- Materials Modeling and Characterization Department, KIMS, Changwon, Korea
| | - Woo-Suk Noh
- MPPC-CPM, Max Planck POSTECH/Korea Research Initiative, Pohang, Korea
| | - J Y Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, Korea
| | - Gyu Seung Choi
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, Korea.,Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Minhyuk Choi
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, Korea.,Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Eunseok Oh
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, Korea.,Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - J -H Park
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea.,MPPC-CPM, Max Planck POSTECH/Korea Research Initiative, Pohang, Korea
| | - Youn Jung Jo
- Department of Physics, Kyungpook National University, Daegu, Korea
| | - Han Woong Yeom
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, Korea.,Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Si-Young Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Korea.
| | - Ji Hoon Shim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea. .,Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, Korea.
| | - Jun Sung Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, Korea. .,Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Korea.
| |
Collapse
|
23
|
González-Hernández R, Šmejkal L, Výborný K, Yahagi Y, Sinova J, Jungwirth T, Železný J. Efficient Electrical Spin Splitter Based on Nonrelativistic Collinear Antiferromagnetism. PHYSICAL REVIEW LETTERS 2021; 126:127701. [PMID: 33834809 DOI: 10.1103/physrevlett.126.127701] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 01/07/2021] [Accepted: 02/23/2021] [Indexed: 06/12/2023]
Abstract
Spin-current generation by electrical means is among the core phenomena driving the field of spintronics. Using ab initio calculations we show that a room-temperature metallic collinear antiferromagnet RuO_{2} allows for highly efficient spin-current generation, arising from anisotropically spin-split bands with conserved up and down spins along the Néel vector axis. The zero net moment antiferromagnet acts as an electrical spin splitter with a 34° propagation angle between spin-up and spin-down currents. The corresponding spin conductivity is a factor of 3 larger than the record value from a survey of 20 000 nonmagnetic spin-Hall materials. We propose a versatile spin-splitter-torque concept circumventing limitations of spin-transfer and spin-orbit torques in present magnetic memory devices.
Collapse
Affiliation(s)
- Rafael González-Hernández
- Grup de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla 081008, Colombia
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - Libor Šmejkal
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
| | - Karel Výborný
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - Yuta Yahagi
- Department of Applied Physics, Tohoku University, Sendai 980-8579, Japan
| | - Jairo Sinova
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - Tomáš Jungwirth
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Jakub Železný
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| |
Collapse
|
24
|
Aryal S, Paudyal D, Pati R. Cr-Doped Ge-Core/Si-Shell Nanowire: An Antiferromagnetic Semiconductor. NANO LETTERS 2021; 21:1856-1862. [PMID: 33577344 DOI: 10.1021/acs.nanolett.0c04971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
An antiferromagnet offers many important functionalities such as opportunities for electrical control of magnetic domains, immunity from magnetic perturbations, and fast spin dynamics. Introducing some of these intriguing features of an antiferromagnet into a low dimensional semiconductor core-shell nanowire offers an exciting pathway for its usage in antiferromagnetic semiconductor spintronics. Here, using a quantum mechanical approach, we predict that the Cr-doped Ge-core/Si-shell nanowire behaves as an antiferromagnetic semiconductor. The origin of antiferromagnetic spin alignments between Cr is attributed to the superexchange interaction mediated by the pz orbitals of the Ge atoms that are bonded to Cr. A weak spin-orbit interaction was found in this material, suggesting a longer spin coherence length. The spin-dependent quantum transport calculations in the Cr-doped nanowire junction reveals a switching feature with a high ON/OFF current ratio (∼41 times higher for the ON state at a relatively small bias of 0.83 V).
Collapse
Affiliation(s)
- Sandip Aryal
- Department of Physics, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Durga Paudyal
- The Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, United States
- Electrical and Computer Engineering Department, Iowa State University, Ames, Iowa 50011, United States
| | - Ranjit Pati
- Department of Physics, Michigan Technological University, Houghton, Michigan 49931, United States
- Henes Center for Quantum Phenomena, Michigan Technological University, Houghton, Michigan 49931, United States
| |
Collapse
|
25
|
Zhang S, Xu R, Luo N, Zou X. Two-dimensional magnetic materials: structures, properties and external controls. NANOSCALE 2021; 13:1398-1424. [PMID: 33416064 DOI: 10.1039/d0nr06813f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Since the discovery of intrinsic ferromagnetism in atomically thin Cr2Gr2Te6 and CrI3 in 2017, research on two-dimensional (2D) magnetic materials has become a highlighted topic. Based on 2D magnetic materials and their heterostructures, exotic physical phenomena at the atomically thin limit have been discovered, such as the quantum anomalous Hall effect, magneto-electric multiferroics, and magnon valleytronics. Furthermore, magnetism in these ultrathin magnets can be effectively controlled by external perturbations, such as electric field, strain, doping, chemical functionalization, and stacking engineering. These attributes make 2D magnets ideal platforms for fundamental research and promising candidates for various spintronic applications. This review aims at providing an overview of the structures, properties, and external controls of 2D magnets, as well as the challenges and potential opportunities in this field.
Collapse
Affiliation(s)
- Shuqing Zhang
- Shenzhen Geim Graphene Center (SGC), Tsinghua-Berkeley Shenzhen Institute (TBSI) & Tsinghua Shenzhen International Graduate School (TSIGS), Tsinghua University, Shenzhen 518055, China.
| | | | | | | |
Collapse
|
26
|
Maniv E, Nair NL, Haley SC, Doyle S, John C, Cabrini S, Maniv A, Ramakrishna SK, Tang YL, Ercius P, Ramesh R, Tserkovnyak Y, Reyes AP, Analytis JG. Antiferromagnetic switching driven by the collective dynamics of a coexisting spin glass. SCIENCE ADVANCES 2021; 7:7/2/eabd8452. [PMID: 33523993 PMCID: PMC7793592 DOI: 10.1126/sciadv.abd8452] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 11/12/2020] [Indexed: 06/02/2023]
Abstract
The theory behind the electrical switching of antiferromagnets is premised on the existence of a well-defined broken symmetry state that can be rotated to encode information. A spin glass is, in many ways, the antithesis of this state, characterized by an ergodic landscape of nearly degenerate magnetic configurations, choosing to freeze into a distribution of these in a manner that is seemingly bereft of information. Here, we show that the coexistence of spin glass and antiferromagnetic order allows a novel mechanism to facilitate the switching of the antiferromagnet Fe1/3 + δNbS2, rooted in the electrically stimulated collective winding of the spin glass. The local texture of the spin glass opens an anisotropic channel of interaction that can be used to rotate the equilibrium orientation of the antiferromagnetic state. Manipulating antiferromagnetic spin textures using a spin glass' collective dynamics opens the field of antiferromagnetic spintronics to new material platforms with complex magnetic textures.
Collapse
Affiliation(s)
- Eran Maniv
- Department of Physics, University of California, Berkeley, CA 94720, USA.
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Nityan L Nair
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Shannon C Haley
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Spencer Doyle
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Caolan John
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Stefano Cabrini
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ariel Maniv
- NRCN, P.O. Box 9001, Beer Sheva, 84190, Israel
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | | | - Yun-Long Tang
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Peter Ercius
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ramamoorthy Ramesh
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Arneil P Reyes
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - James G Analytis
- Department of Physics, University of California, Berkeley, CA 94720, USA.
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| |
Collapse
|
27
|
Du EW, Gong SJ, Tang X, Chu J, Rappe AM, Gong C. Ferroelectric Switching of Pure Spin Polarization in Two-Dimensional Electron Gas. NANO LETTERS 2020; 20:7230-7236. [PMID: 32786931 DOI: 10.1021/acs.nanolett.0c02584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional electron gas (2DEG) created at compound interfaces can exhibit a broad range of exotic physical phenomena, including quantum Hall phase, emergent ferromagnetism, and superconductivity. Although electron spin plays key roles in these phenomena, the fundamental understanding and application prospects of such emergent interfacial states have been largely impeded by the lack of purely spin-polarized 2DEG. In this work, by first-principles calculations of the multiferroic superlattice GeTe/MnTe, we find the ferroelectric polarization of GeTe is concurrent with the half-metallic 2DEG at interfaces. Remarkably, the pure spin polarization of the 2DEG can be created and annihilated by polarizing and depolarizing the ferroelectrics and can be switched (between pure spin-up and pure spin-down) by flipping the ferroelectric polarization. Given the electric-field amplification effect of ferroelectric electronics, we envision multiferroic superlattices could open up new opportunities for low-power, high-efficiency spintronic devices such as spin field-effect transistors.
Collapse
Affiliation(s)
- Er-Wei Du
- Key Laboratory of Polar Materials and Devices (MOE), Department of Optoelectronics, East China Normal University, Shanghai 200241, China
| | - Shi-Jing Gong
- Key Laboratory of Polar Materials and Devices (MOE), Department of Optoelectronics, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Shanghai Institute of Intelligent Electronics & Systems, Fudan University, Shanghai 200433, China
| | - Xiaodong Tang
- Key Laboratory of Polar Materials and Devices (MOE), Department of Optoelectronics, East China Normal University, Shanghai 200241, China
| | - Junhao Chu
- Department of Materials Science, Fudan University, Shanghai 200433, China
| | - Andrew M Rappe
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Cheng Gong
- Department of Electrical and Computer Engineering and Quantum Technology Center, University of Maryland, College Park, Maryland 20742, United States
| |
Collapse
|
28
|
Little A, Lee C, John C, Doyle S, Maniv E, Nair NL, Chen W, Rees D, Venderbos JWF, Fernandes RM, Analytis JG, Orenstein J. Three-state nematicity in the triangular lattice antiferromagnet Fe 1/3NbS 2. NATURE MATERIALS 2020; 19:1062-1067. [PMID: 32424369 DOI: 10.1038/s41563-020-0681-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
Nematic order is the breaking of rotational symmetry in the presence of translational invariance. While originally defined in the context of liquid crystals, the concept of nematic order has arisen in crystalline matter with discrete rotational symmetry, most prominently in the tetragonal Fe-based superconductors where the parent state is four-fold symmetric. In this case the nematic director takes on only two directions, and the order parameter in such 'Ising-nematic' systems is a simple scalar. Here, using a spatially resolved optical polarimetry technique, we show that a qualitatively distinct nematic state arises in the triangular lattice antiferromagnet Fe1/3NbS2. The crucial difference is that the nematic order on the triangular lattice is a [Formula: see text] or three-state Potts-nematic order parameter. As a consequence, the anisotropy axes of response functions such as the resistivity tensor can be continuously reoriented by external perturbations. This discovery lays the groundwork for devices that exploit analogies with nematic liquid crystals.
Collapse
Affiliation(s)
- Arielle Little
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Changmin Lee
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Caolan John
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Spencer Doyle
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Eran Maniv
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Nityan L Nair
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Wenqin Chen
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Dylan Rees
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jörn W F Venderbos
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA
- Department of Physics, Drexel University, Philadelphia, PA, USA
| | - Rafael M Fernandes
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - James G Analytis
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Joseph Orenstein
- Department of Physics, University of California, Berkeley, CA, USA.
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| |
Collapse
|
29
|
Cao Q, Lü W, Wang XR, Guan X, Wang L, Yan S, Wu T, Wang X. Nonvolatile Multistates Memories for High-Density Data Storage. ACS APPLIED MATERIALS & INTERFACES 2020; 12:42449-42471. [PMID: 32812741 DOI: 10.1021/acsami.0c10184] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In the current information age, the realization of memory devices with energy efficient design, high storage density, nonvolatility, fast access, and low cost is still a great challenge. As a promising technology to meet these stringent requirements, nonvolatile multistates memory (NMSM) has attracted lots of attention over the past years. Owing to the capability to store data in more than a single bit (0 or 1), the storage density is dramatically enhanced without scaling down the memory cell, making memory devices more efficient and less expensive. Multistates in a single cell also provide an unconventional in-memory computing platform beyond the Von Neumann architecture and enable neuromorphic computing with low power consumption. In this review, an in-depth perspective is presented on the recent progress and challenges on the device architectures, material innovation, working mechanisms of various types of NMSMs, including flash, magnetic random-access memory (MRAM), resistive random-access memory (RRAM), ferroelectric random-access memory (FeRAM), and phase-change memory (PCM). The intriguing properties and performance of these NMSMs, which are the key to realizing highly integrated memory hierarchy, are discussed and compared.
Collapse
Affiliation(s)
- Qiang Cao
- Spintronics Institute, University of Jinan, Jinan 250022, China
| | - Weiming Lü
- Spintronics Institute, University of Jinan, Jinan 250022, China
| | - X Renshaw Wang
- School of Physical and Mathematical Sciences & School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore
| | - Xinwei Guan
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Lan Wang
- School of Science, ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT University, Melbourne, Victoria 3001, Australia
| | - Shishen Yan
- Spintronics Institute, University of Jinan, Jinan 250022, China
| | - Tom Wu
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | | |
Collapse
|
30
|
Hou F, Yao Q, Zhou CS, Ma XM, Han M, Hao YJ, Wu X, Zhang Y, Sun H, Liu C, Zhao Y, Liu Q, Lin J. Te-Vacancy-Induced Surface Collapse and Reconstruction in Antiferromagnetic Topological Insulator MnBi 2Te 4. ACS NANO 2020; 14:11262-11272. [PMID: 32813492 DOI: 10.1021/acsnano.0c03149] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
MnBi2Te4 is an antiferromagnetic topological insulator that has stimulated intense interest due to its exotic quantum phenomena and promising device applications. The surface structure is a determinant factor to understand the magnetic and topological behavior of MnBi2Te4, yet its precise atomic structure remains elusive. Here we discovered a surface collapse and reconstruction of few-layer MnBi2Te4 exfoliated under delicate protection. Instead of the ideal septuple-layer structure in the bulk, the collapsed surface is shown to reconstruct as a Mn-doped Bi2Te3 quintuple layer and a MnxBiyTe double layer with a clear van der Waals gap in between. Combined with first-principles calculations, such surface collapse is attributed to the abundant intrinsic Mn-Bi antisite defects and the tellurium vacancy in the exfoliated surface, which is further supported by in situ annealing and electron irradiation experiments. Our results shed light on the understanding of the intricate surface-bulk correspondence of MnBi2Te4 and provide an insightful perspective on the surface-related quantum measurements in MnBi2Te4 few-layer devices.
Collapse
Affiliation(s)
- Fuchen Hou
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
- Shenzhen Key Laboratory of for Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China
| | - Qiushi Yao
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
| | - Chun-Sheng Zhou
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
| | - Xiao-Ming Ma
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
| | - Mengjiao Han
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
- Shenzhen Key Laboratory of for Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yu-Jie Hao
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
| | - Xuefeng Wu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
| | - Yu Zhang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
- Department of Physics, University of Hong Kong, Hong Kong, P. R. China
| | - Hongyi Sun
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
| | - Chang Liu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Yue Zhao
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Qihang Liu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
- Guangdong Provincial Key Laboratory for Computational Science and Material Design, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Key Laboratory of for Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China
| | - Junhao Lin
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, P. R. China
- Shenzhen Key Laboratory of for Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China
| |
Collapse
|
31
|
Slęzak M, Dróżdż P, Janus W, Nayyef H, Kozioł-Rachwał A, Szpytma M, Zając M, Menteş TO, Genuzio F, Locatelli A, Slęzak T. Fine tuning of ferromagnet/antiferromagnet interface magnetic anisotropy for field-free switching of antiferromagnetic spins. NANOSCALE 2020; 12:18091-18095. [PMID: 32856646 DOI: 10.1039/d0nr04193a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We show that in a uniform thickness NiO(111)/Fe(110) epitaxial bilayer system, at given temperature near 300 K, two magnetic states with orthogonal spin orientations can be stabilized in antiferromagnetic NiO. Field-free, reversible switching between these two antiferromagnetic states is demonstrated. The observed phenomena arise from the unique combination of precisely tuned interface magnetic anisotropy, thermal hysteresis of spin reorientation transition and interfacial ferromagnet/antiferromagnet exchange coupling. The possibility of field-free switching between two magnetic states in an antiferromagnet is fundamentally interesting and can lead to new ideas in heat assisted magnetic recording technology.
Collapse
Affiliation(s)
- M Slęzak
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - P Dróżdż
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - W Janus
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - H Nayyef
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - A Kozioł-Rachwał
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - M Szpytma
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - M Zając
- National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, Kraków, Poland
| | - T O Menteş
- Elettra - Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - F Genuzio
- Elettra - Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - A Locatelli
- Elettra - Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - T Slęzak
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| |
Collapse
|
32
|
Liu H, Wang X, Wu J, Chen Y, Wan J, Wen R, Yang J, Liu Y, Song Z, Xie L. Vapor Deposition of Magnetic Van der Waals NiI 2 Crystals. ACS NANO 2020; 14:10544-10551. [PMID: 32806048 DOI: 10.1021/acsnano.0c04499] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The recent discovery of van der Waals magnetic materials has attracted great attention in materials science and spintronics. The preparation of ultrathin magnetic layers down to atomic thickness is challenging and is mostly by mechanical exfoliation. Here, we report vapor deposition of magnetic van der Waals NiI2 crystals. Two-dimensional (2D) NiI2 flakes are grown on SiO2/Si substrates with a thickness of 5-40 nm and on hexagonal boron nitride (h-BN) down to monolayer thickness. Temperature-dependent Raman spectroscopy reveals robust magnetic phase transitions in the as-grown 2D NiI2 crystals down to trilayer. Electrical measurements show a semiconducting transport behavior with a high on/off ratio of 106 for the NiI2 flakes. Lastly, density functional theory calculation shows an intralayer ferromagnetic and interlayer antiferromagnetic ordering in 2D NiI2. This work provides a feasible approach to epitaxy 2D magnetic transition metal halides and also offers atomically thin materials for spintronic devices.
Collapse
Affiliation(s)
- Haining Liu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- College of Chemistry and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China
| | - Xinsheng Wang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Juanxia Wu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Yuansha Chen
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jing Wan
- Key Laboratory of Molecular Nanostructure and Nanotechnology, Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Rui Wen
- Key Laboratory of Molecular Nanostructure and Nanotechnology, Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Jinbo Yang
- State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871, China
| | - Ying Liu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Zhigang Song
- State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871, China
| | - Liming Xie
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
33
|
Lu C, Liu JM. The J eff = 1/2 Antiferromagnet Sr 2 IrO 4 : A Golden Avenue toward New Physics and Functions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1904508. [PMID: 31667943 DOI: 10.1002/adma.201904508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 09/12/2019] [Indexed: 06/10/2023]
Abstract
Iridates have been providing a fertile ground for studying emergent phases of matter that arise from the delicate interplay of various fundamental interactions with approximate energy scale. Among these highly focused quantum materials, the perovskite Sr2 IrO4 , which belongs to the Ruddlesden-Popper series, stands out and has been intensively addressed in the last decade, since it hosts a novel Jeff = 1/2 state that is a profound manifestation of strong spin-orbit coupling. Moreover, the Jeff = 1/2 state represents a rare example of iridates that is better understood both theoretically and experimentally. Here, Sr2 IrO4 is taken as an example to review the recent advances of the Jeff = 1/2 state in two aspects: materials fundamentals and functionality potentials. In the fundamentals part, the basic issues for the layered canted antiferromagnetic order of the Jeff = 1/2 magnetic moments in Sr2 IrO4 are illustrated, and then the progress of the antiferromagnetic order modulation through diverse routes is highlighted. Subsequently, for the functionality potentials, fascinating properties such as atomic-scale giant magnetoresistance, anisotropic magnetoresistance, and nonvolatile memory, are addressed. To conclude, prospective remarks and an outlook are given.
Collapse
Affiliation(s)
- Chengliang Lu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jun-Ming Liu
- Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and Institute for Advanced Materials, South China Normal University, Guangzhou, 510006, China
| |
Collapse
|
34
|
Maruhashi K, Takahashi KS, Bahramy MS, Shimizu S, Kurihara R, Miyake A, Tokunaga M, Tokura Y, Kawasaki M. Anisotropic Quantum Transport through a Single Spin Channel in the Magnetic Semiconductor EuTiO 3. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1908315. [PMID: 32383210 DOI: 10.1002/adma.201908315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/12/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Magnetic semiconductors are a vital component in the understanding of quantum transport phenomena. To explore such delicate, yet fundamentally important, effects, it is crucial to maintain a high carrier mobility in the presence of magnetic moments. In practice, however, magnetization often diminishes the carrier mobility. Here, it is shown that EuTiO3 is a rare example of a magnetic semiconductor that can be desirably grown using the molecular beam epitaxy to possess a high carrier mobility exceeding 3000 cm2 V-1 s-1 at 2 K, while intrinsically hosting a large magnetization value, 7 μB per formula unit. This is demonstrated by measuring the Shubnikov-de Haas (SdH) oscillations in the ferromagnetic state of EuTiO3 films with various carrier densities. Using first-principles calculations, it is shown that the observed SdH oscillations originate genuinely from Ti 3d-t2g states which are fully spin-polarized due to their energetical proximity to the in-gap Eu 4f bands. Such an exchange coupling is further shown to have a profound effect on the effective mass and fermiology of the Ti 3d-t2g electrons, manifested by a directional anisotropy in the SdH oscillations. These findings suggest that EuTiO3 film is an ideal magnetic semiconductor, offering a fertile field to explore quantum phenomena suitable for spintronic applications.
Collapse
Affiliation(s)
- Kazuki Maruhashi
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo, 113-8656, Japan
| | - Kei S Takahashi
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo, 102-0075, Japan
| | - Mohammad Saeed Bahramy
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Sunao Shimizu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Ryosuke Kurihara
- Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Atsushi Miyake
- Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Masashi Tokunaga
- Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Yoshinori Tokura
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Masashi Kawasaki
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| |
Collapse
|
35
|
Vaidya P, Morley SA, van Tol J, Liu Y, Cheng R, Brataas A, Lederman D, del Barco E. Subterahertz spin pumping from an insulating antiferromagnet. Science 2020; 368:160-165. [DOI: 10.1126/science.aaz4247] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 03/12/2020] [Indexed: 11/02/2022]
Affiliation(s)
- Priyanka Vaidya
- Department of Physics, University of Central Florida, Orlando, FL 32765, USA
| | - Sophie A. Morley
- Department of Physics, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Johan van Tol
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | - Yan Liu
- College of Sciences, Northeastern University, Shenyang, Liaoning, China
| | - Ran Cheng
- Department of Electrical and Computer Engineering and Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA
| | - Arne Brataas
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - David Lederman
- Department of Physics, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Enrique del Barco
- Department of Physics, University of Central Florida, Orlando, FL 32765, USA
| |
Collapse
|
36
|
Nair NL, Maniv E, John C, Doyle S, Orenstein J, Analytis JG. Electrical switching in a magnetically intercalated transition metal dichalcogenide. NATURE MATERIALS 2020; 19:153-157. [PMID: 31685945 DOI: 10.1038/s41563-019-0518-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 09/19/2019] [Indexed: 06/10/2023]
Abstract
Advances in controlling the correlated behaviour of transition metal dichalcogenides have opened a new frontier of many-body physics in two dimensions. A field where these materials have yet to make a deep impact is antiferromagnetic spintronics-a relatively new research direction promising technologies with fast switching times, insensitivity to magnetic perturbations and reduced cross-talk1-3. Here, we present measurements on the intercalated transition metal dichalcogenide Fe1/3NbS2 that exhibits antiferromagnetic ordering below 42 K (refs. 4,5). We find that remarkably low current densities of the order of 104 A cm-2 can reorient the magnetic order, which can be detected through changes in the sample resistance, demonstrating its use as an electronically accessible antiferromagnetic switch. Fe1/3NbS2 is part of a larger family of magnetically intercalated transition metal dichalcogenides, some of which may exhibit switching at room temperature, forming a platform from which to build tuneable antiferromagnetic spintronic devices6,7.
Collapse
Affiliation(s)
- Nityan L Nair
- Department of Physics, University of California, Berkeley, CA, USA.
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Eran Maniv
- Department of Physics, University of California, Berkeley, CA, USA.
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Caolan John
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Spencer Doyle
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - J Orenstein
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - James G Analytis
- Department of Physics, University of California, Berkeley, CA, USA.
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| |
Collapse
|
37
|
Spin current from sub-terahertz-generated antiferromagnetic magnons. Nature 2020; 578:70-74. [PMID: 31988510 DOI: 10.1038/s41586-020-1950-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 10/22/2019] [Indexed: 11/08/2022]
Abstract
Spin dynamics in antiferromagnets has much shorter timescales than in ferromagnets, offering attractive properties for potential applications in ultrafast devices1-3. However, spin-current generation via antiferromagnetic resonance and simultaneous electrical detection by the inverse spin Hall effect in heavy metals have not yet been explicitly demonstrated4-6. Here we report sub-terahertz spin pumping in heterostructures of a uniaxial antiferromagnetic Cr2O3 crystal and a heavy metal (Pt or Ta in its β phase). At 0.240 terahertz, the antiferromagnetic resonance in Cr2O3 occurs at about 2.7 tesla, which excites only right-handed magnons. In the spin-canting state, another resonance occurs at 10.5 tesla from the precession of induced magnetic moments. Both resonances generate pure spin currents in the heterostructures, which are detected by the heavy metal as peaks or dips in the open-circuit voltage. The pure-spin-current nature of the electrically detected signals is unambiguously confirmed by the reversal of the voltage polarity observed under two conditions: when switching the detector metal from Pt to Ta, reversing the sign of the spin Hall angle7-9, and when flipping the magnetic-field direction, reversing the magnon chirality4,5. The temperature dependence of the electrical signals at both resonances suggests that the spin current contains both coherent and incoherent magnon contributions, which is further confirmed by measurements of the spin Seebeck effect and is well described by a phenomenological theory. These findings reveal the unique characteristics of magnon excitations in antiferromagnets and their distinctive roles in spin-charge conversion in the high-frequency regime.
Collapse
|
38
|
Shimura Y, Zhang Q, Zeng B, Rhodes D, Schönemann R, Tsujimoto M, Matsumoto Y, Sakai A, Sakakibara T, Araki K, Zheng W, Zhou Q, Balicas L, Nakatsuji S. Giant Anisotropic Magnetoresistance due to Purely Orbital Rearrangement in the Quadrupolar Heavy Fermion Superconductor PrV_{2}Al_{20}. PHYSICAL REVIEW LETTERS 2019; 122:256601. [PMID: 31347904 DOI: 10.1103/physrevlett.122.256601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Indexed: 06/10/2023]
Abstract
We report the discovery of giant and anisotropic magnetoresistance due to the orbital rearrangement in a non magnetic correlated metal. In particular, we measured the magnetoresistance under fields up to 31.4 T in the cubic Pr-based heavy fermion superconductor PrV_{2}Al_{20} with a non magnetic Γ_{3} doublet ground state, exhibiting antiferroquadrupole ordering below 0.7 K. For the [100] direction, we find that the high-field phase appears between 12 and 25 T, accompanied by a large jump at 12 T in the magnetoresistance (ΔMR∼100%) and in the anisotropic magnetoresistivity ratio by ∼20%. These observations indicate that the strong hybridization between the conduction electrons and anisotropic quadrupole moments leads to the Fermi surface reconstruction upon crossing the field-induced antiferroquadrupole (orbital) rearrangement.
Collapse
Affiliation(s)
- Yasuyuki Shimura
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Qiu Zhang
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Bin Zeng
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Daniel Rhodes
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Rico Schönemann
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Masaki Tsujimoto
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yosuke Matsumoto
- Department of Quantum Materials, Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - Akito Sakai
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Toshiro Sakakibara
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Koji Araki
- Department of Applied Physics, National Defense Academy, Yokosuka, Kanagawa 239-8686, Japan
| | - Wenkai Zheng
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Qiong Zhou
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Luis Balicas
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Satoru Nakatsuji
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| |
Collapse
|
39
|
Giant anisotropic magnetoresistance and nonvolatile memory in canted antiferromagnet Sr 2IrO 4. Nat Commun 2019; 10:2280. [PMID: 31123257 PMCID: PMC6533248 DOI: 10.1038/s41467-019-10299-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 05/02/2019] [Indexed: 11/09/2022] Open
Abstract
Antiferromagnets have been generating intense interest in the spintronics community, owing to their intrinsic appealing properties like zero stray field and ultrafast spin dynamics. While the control of antiferromagnetic (AFM) orders has been realized by various means, applicably appreciated functionalities on the readout side of AFM-based devices are urgently desired. Here, we report the remarkably enhanced anisotropic magnetoresistance (AMR) as giant as ~160% in a simple resistor structure made of AFM Sr2IrO4 without auxiliary reference layer. The underlying mechanism for the giant AMR is an indispensable combination of atomic scale giant-MR-like effect and magnetocrystalline anisotropy energy, which was not accessed earlier. Furthermore, we demonstrate the bistable nonvolatile memory states that can be switched in-situ without the inconvenient heat-assisted procedure, and robustly preserved even at zero magnetic field, due to the modified interlayer coupling by 1% Ga-doping in Sr2IrO4. These findings represent a straightforward step toward the AFM spintronic devices.
Collapse
|
40
|
Yin G, Yu JX, Liu Y, Lake RK, Zang J, Wang KL. Planar Hall Effect in Antiferromagnetic MnTe Thin Films. PHYSICAL REVIEW LETTERS 2019; 122:106602. [PMID: 30932676 DOI: 10.1103/physrevlett.122.106602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 01/10/2019] [Indexed: 06/09/2023]
Abstract
We show that the spin-orbit coupling (SOC) in α-MnTe impacts the transport behavior by generating an anisotropic valence-band splitting, resulting in four spin-polarized pockets near Γ. A minimal k·p model is constructed to capture this splitting by group theory analysis, a tight-binding model, and ab initio calculations. The model is shown to describe the rotation symmetry of the zero-field planer Hall effect (PHE). The PHE originates from the band anisotropy given by SOC, and is quantitatively estimated to be 25%-31% for an ideal thin film with a single antiferromagnetic domain.
Collapse
Affiliation(s)
- Gen Yin
- Department of Electrical and Computer Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA
| | - Jie-Xiang Yu
- Department of Physics and Materials Science Program, University of New Hampshire, Durham, New Hampshire 03824, USA
| | - Yizhou Liu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Laboratory for Terascale and Terahertz Electronics (LATTE), Department of Electrical and Computer Engineering, University of California-Riverside, Riverside, California 92521, USA
| | - Roger K Lake
- Laboratory for Terascale and Terahertz Electronics (LATTE), Department of Electrical and Computer Engineering, University of California-Riverside, Riverside, California 92521, USA
| | - Jiadong Zang
- Department of Physics and Materials Science Program, University of New Hampshire, Durham, New Hampshire 03824, USA
| | - Kang L Wang
- Department of Electrical and Computer Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA
- Department of Physics and Astronomy, University of California-Los Angeles, Los Angeles, California 90095, USA
| |
Collapse
|
41
|
Lee N, Ko E, Choi HY, Hong YJ, Nauman M, Kang W, Choi HJ, Choi YJ, Jo Y. Antiferromagnet-Based Spintronic Functionality by Controlling Isospin Domains in a Layered Perovskite Iridate. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1805564. [PMID: 30370684 DOI: 10.1002/adma.201805564] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/09/2018] [Indexed: 06/08/2023]
Abstract
The novel electronic state of the canted antiferromagnetic (AFM) insulator strontium iridate (Sr2 IrO4 ) is well described by the spin-orbit-entangled isospin Jeff = 1/2, but the role of isospin in transport phenomena remains poorly understood. In this study, antiferromagnet-based spintronic functionality is demonstrated by combining the unique characteristics of the isospin state in Sr2 IrO4 . Based on magnetic and transport measurements, a large and highly anisotropic magnetoresistance (AMR) is obtained by manipulating the AFM isospin domains. First-principles calculations suggest that electrons whose isospin directions are strongly coupled to the in-plane net magnetic moment encounter an isospin mismatch when moving across the AFM domain boundaries, which generates a high resistance state. By rotating a magnetic field that aligns in-plane net moments and removes domain boundaries, the macroscopically ordered isospins govern dynamic transport through the system, which leads to the extremely angle-sensitive AMR. As this work establishes a link between isospins and magnetotransport in strongly spin-orbit-coupled AFM Sr2 IrO4 , the peculiar AMR effect provides a beneficial foundation for fundamental and applied research on AFM spintronics.
Collapse
Affiliation(s)
- Nara Lee
- Department of Physics, Yonsei University, Seoul, 03722, Korea
| | - Eunjung Ko
- Department of Physics, Yonsei University, Seoul, 03722, Korea
| | - Hwan Young Choi
- Department of Physics, Yonsei University, Seoul, 03722, Korea
| | - Yun Jeong Hong
- Department of Physics, Kyungpook National University, Daegu, 41566, Korea
| | - Muhammad Nauman
- Department of Physics, Kyungpook National University, Daegu, 41566, Korea
| | - Woun Kang
- Department of Physics, Ewha Womans University, Seoul, 03760, Korea
| | | | - Young Jai Choi
- Department of Physics, Yonsei University, Seoul, 03722, Korea
| | - Younjung Jo
- Department of Physics, Kyungpook National University, Daegu, 41566, Korea
| |
Collapse
|
42
|
Godinho J, Reichlová H, Kriegner D, Novák V, Olejník K, Kašpar Z, Šobáň Z, Wadley P, Campion RP, Otxoa RM, Roy PE, Železný J, Jungwirth T, Wunderlich J. Electrically induced and detected Néel vector reversal in a collinear antiferromagnet. Nat Commun 2018; 9:4686. [PMID: 30409971 PMCID: PMC6224378 DOI: 10.1038/s41467-018-07092-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/10/2018] [Indexed: 11/09/2022] Open
Abstract
Antiferromagnets are enriching spintronics research by many favorable properties that include insensitivity to magnetic fields, neuromorphic memory characteristics, and ultra-fast spin dynamics. Designing memory devices with electrical writing and reading is one of the central topics of antiferromagnetic spintronics. So far, such a combined functionality has been demonstrated via 90° reorientations of the Néel vector generated by the current-induced spin orbit torque and sensed by the linear-response anisotropic magnetoresistance. Here we show that in the same antiferromagnetic CuMnAs films as used in these earlier experiments we can also control 180° Néel vector reversals by switching the polarity of the writing current. Moreover, the two stable states with opposite Néel vector orientations in this collinear antiferromagnet can be electrically distinguished by measuring a second-order magnetoresistance effect. We discuss the general magnetic point group symmetries allowing for this electrical readout effect and its specific microscopic origin in CuMnAs.
Collapse
Affiliation(s)
- J Godinho
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic. .,Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 12116, Prague 2, Czech Republic.
| | - H Reichlová
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic.,Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
| | - D Kriegner
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic.,Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - V Novák
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - K Olejník
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - Z Kašpar
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - Z Šobáň
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - P Wadley
- School of Physics and Astronomy, University Of Nottingham, NG7 2RD, Nottingham, United Kingdom
| | - R P Campion
- School of Physics and Astronomy, University Of Nottingham, NG7 2RD, Nottingham, United Kingdom
| | - R M Otxoa
- Hitachi Cambridge Laboratory, Hitachi Europe LTD, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.,Donostia International Physics Center, Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, 20018, Spain
| | - P E Roy
- Hitachi Cambridge Laboratory, Hitachi Europe LTD, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom
| | - J Železný
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - T Jungwirth
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic.,School of Physics and Astronomy, University Of Nottingham, NG7 2RD, Nottingham, United Kingdom
| | - J Wunderlich
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic. .,Hitachi Cambridge Laboratory, Hitachi Europe LTD, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.
| |
Collapse
|
43
|
Moriyama T, Zhou W, Seki T, Takanashi K, Ono T. Spin-Orbit-Torque Memory Operation of Synthetic Antiferromagnets. PHYSICAL REVIEW LETTERS 2018; 121:167202. [PMID: 30387670 DOI: 10.1103/physrevlett.121.167202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Indexed: 06/08/2023]
Abstract
In this Letter, we show the demonstration of a sequential antiferromagnetic memory operation with a spin-orbit-torque write, by the spin Hall effect, and a resistive read in the CoGd synthetic antiferromagnetic bits, in which we reveal the distinct differences in the spin-orbit-torque and field-induced switching mechanisms of the antiferromagnetic moment, or the Néel vector. In addition to the comprehensive spin torque memory operation, our thorough investigations also highlight the high immunity to a field disturbance as well as a memristive behavior of the antiferromagnetic bits.
Collapse
Affiliation(s)
- Takahiro Moriyama
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
- Center for Spintronics Research Network, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - Weinan Zhou
- Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980-8577, Japan
| | - Takeshi Seki
- Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai, Miyagi, 980-8577, Japan
| | - Koki Takanashi
- Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai, Miyagi, 980-8577, Japan
| | - Teruo Ono
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
- Center for Spintronics Research Network, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| |
Collapse
|
44
|
Eremeev SV, Otrokov MM, Chulkov EV. New Universal Type of Interface in the Magnetic Insulator/Topological Insulator Heterostructures. NANO LETTERS 2018; 18:6521-6529. [PMID: 30260648 DOI: 10.1021/acs.nanolett.8b03057] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Magnetic proximity effect at the interface between magnetic and topological insulators (MIs and TIs) is considered to have great potential in spintronics as, in principle, it allows realizing the quantum anomalous Hall and topological magneto-electric effects (QAHE and TME). Although an out-of-plane magnetization induced in a TI by the proximity effect was successfully probed in experiments, first-principles calculations reveal that a strong electrostatic potential mismatch at abrupt MI/TI interfaces creates harmful trivial states rendering both the QAHE and TME unfeasible in practice. Here on the basis of recent progress in formation of planar self-assembled single layer MI/TI heterostructure (T. Hirahara et al. Nano Lett. 2017 , 17 , 3493 - 3500 ), we propose a conceptually new type of the MI/TI interfaces by means of density functional theory calculations. By considering MnSe/Bi2Se3, MnTe/Bi2Te3, and EuS/Bi2Se3 we demonstrate that, instead of a sharp MI/TI interface clearly separating the two subsystems, it is energetically far more favorable to form a built-in interface via insertion of the MI film inside the TI's surface quintuple layer (e.g., Se-Bi-Se-[MnSe]-Bi-Se) where it forms a bulk-like MI structure. This results in a smooth MI-to-TI connection that yields the interface electronic structure essentially free of trivial states. Our findings open a new direction in studies of the MI/TI interfaces and restore their potential for the QAHE and TME observation.
Collapse
Affiliation(s)
- Sergey V Eremeev
- Institute of Strength Physics and Materials Science , Tomsk 634055 , Russia
- Tomsk State University , Tomsk 634050 , Russia
- Saint Petersburg State University , Saint Petersburg 198504 , Russia
- Donostia International Physics Center (DIPC) , Paseo de Manuel Lardizabal, 4 , 20018 San Sebastián/Donostia , Basque Country , Spain
| | - Mikhail M Otrokov
- Tomsk State University , Tomsk 634050 , Russia
- Saint Petersburg State University , Saint Petersburg 198504 , Russia
- Departamento de Física de Materiales UPV/EHU , Centro de Física de Materiales CFM - MPC and Centro Mixto CSIC-UPV/EHU , 20080 San Sebastián/Donostia , Spain
- IKERBASQUE , Basque Foundation for Science , 48011 Bilbao , Spain
| | - Evgueni V Chulkov
- Tomsk State University , Tomsk 634050 , Russia
- Saint Petersburg State University , Saint Petersburg 198504 , Russia
- Donostia International Physics Center (DIPC) , Paseo de Manuel Lardizabal, 4 , 20018 San Sebastián/Donostia , Basque Country , Spain
- Departamento de Física de Materiales UPV/EHU , Centro de Física de Materiales CFM - MPC and Centro Mixto CSIC-UPV/EHU , 20080 San Sebastián/Donostia , Spain
| |
Collapse
|
45
|
Moriyama T, Oda K, Ohkochi T, Kimata M, Ono T. Spin torque control of antiferromagnetic moments in NiO. Sci Rep 2018; 8:14167. [PMID: 30242184 PMCID: PMC6155024 DOI: 10.1038/s41598-018-32508-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 09/03/2018] [Indexed: 11/30/2022] Open
Abstract
For a long time, there were no efficient ways of controlling antiferromagnets. Quite a strong magnetic field was required to manipulate the magnetic moments because of a high molecular field and a small magnetic susceptibility. It was also difficult to detect the orientation of the magnetic moments since the net magnetic moment is effectively zero. For these reasons, research on antiferromagnets has not been progressed as drastically as that on ferromagnets which are the main materials in modern spintronic devices. Here we show that the magnetic moments in NiO, a typical natural antiferromagnet, can indeed be controlled by the spin torque with a relatively small electric current density (~4 × 107 A/cm2) and their orientation is detected by the transverse resistance resulting from the spin Hall magnetoresistance. The demonstrated techniques of controlling and detecting antiferromagnets would outstandingly promote the methodologies in the recently emerged “antiferromagnetic spintronics”. Furthermore, our results essentially lead to a spin torque antiferromagnetic memory.
Collapse
Affiliation(s)
- Takahiro Moriyama
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan. .,Center for Spintronics Research Network, Osaka University, Toyonaka, Osaka, 560-8531, Japan.
| | - Kent Oda
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Takuo Ohkochi
- Japan Synchrotron Radiation Research Institute, Sayo, Hyogo, 679-5198, Japan
| | - Motoi Kimata
- Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980-8577, Japan
| | - Teruo Ono
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan.,Center for Spintronics Research Network, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| |
Collapse
|
46
|
He QL, Yin G, Grutter AJ, Pan L, Che X, Yu G, Gilbert DA, Disseler SM, Liu Y, Shafer P, Zhang B, Wu Y, Kirby BJ, Arenholz E, Lake RK, Han X, Wang KL. Exchange-biasing topological charges by antiferromagnetism. Nat Commun 2018; 9:2767. [PMID: 30018306 PMCID: PMC6050290 DOI: 10.1038/s41467-018-05166-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 05/29/2018] [Indexed: 11/19/2022] Open
Abstract
Geometric Hall effect is induced by the emergent gauge field experienced by the carriers adiabatically passing through certain real-space topological spin textures, which is a probe to non-trivial spin textures, such as magnetic skyrmions. We report experimental indications of spin-texture topological charges induced in heterostructures of a topological insulator (Bi,Sb)2Te3 coupled to an antiferromagnet MnTe. Through a seeding effect, the pinned spins at the interface leads to a tunable modification of the averaged real-space topological charge. This effect experimentally manifests as a modification of the field-dependent geometric Hall effect when the system is field-cooled along different directions. This heterostructure represents a platform for manipulating magnetic topological transitions using antiferromagnetic order.
Collapse
Affiliation(s)
- Qing Lin He
- Department of Electrical and Computer Engineering, Department of Physics and Astronomy, Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA.
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China.
| | - Gen Yin
- Department of Electrical and Computer Engineering, Department of Physics and Astronomy, Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Alexander J Grutter
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899-6102, USA
| | - Lei Pan
- Department of Electrical and Computer Engineering, Department of Physics and Astronomy, Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Xiaoyu Che
- Department of Electrical and Computer Engineering, Department of Physics and Astronomy, Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Guoqiang Yu
- Department of Electrical and Computer Engineering, Department of Physics and Astronomy, Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Dustin A Gilbert
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899-6102, USA
| | - Steven M Disseler
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899-6102, USA
| | - Yizhou Liu
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, 92521-0204, USA
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Bin Zhang
- Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing, 100124, China
| | - Yingying Wu
- Department of Electrical and Computer Engineering, Department of Physics and Astronomy, Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Brian J Kirby
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899-6102, USA
| | - Elke Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Roger K Lake
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, 92521-0204, USA
| | - Xiaodong Han
- Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing, 100124, China
| | - Kang L Wang
- Department of Electrical and Computer Engineering, Department of Physics and Astronomy, Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA.
| |
Collapse
|
47
|
Siol S, Holder A, Steffes J, Schelhas LT, Stone KH, Garten L, Perkins JD, Parilla PA, Toney MF, Huey BD, Tumas W, Lany S, Zakutayev A. Negative-pressure polymorphs made by heterostructural alloying. SCIENCE ADVANCES 2018; 4:eaaq1442. [PMID: 29725620 PMCID: PMC5930396 DOI: 10.1126/sciadv.aaq1442] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 03/07/2018] [Indexed: 06/01/2023]
Abstract
The ability of a material to adopt multiple structures, known as polymorphism, is a fascinating natural phenomenon. Various polymorphs with unusual properties are routinely synthesized by compression under positive pressure. However, changing a material's structure by applying tension under negative pressure is much more difficult. We show how negative-pressure polymorphs can be synthesized by mixing materials with different crystal structures-a general approach that should be applicable to many materials. Theoretical calculations suggest that it costs less energy to mix low-density structures than high-density structures, due to less competition for space between the atoms. Proof-of-concept experiments confirm that mixing two different high-density forms of MnSe and MnTe stabilizes a Mn(Se,Te) alloy with a low-density wurtzite structure. This Mn(Se,Te) negative-pressure polymorph has 2× to 4× lower electron effective mass compared to MnSe and MnTe parent compounds and has a piezoelectric response that none of the parent compounds have. This example shows how heterostructural alloying can lead to negative-pressure polymorphs with useful properties-materials that are otherwise nearly impossible to make.
Collapse
Affiliation(s)
- Sebastian Siol
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Aaron Holder
- National Renewable Energy Laboratory, Golden, CO 80401, USA
- University of Colorado, Boulder, CO 80309, USA
| | | | | | - Kevin H. Stone
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Lauren Garten
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | | | | | | | | | - William Tumas
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Stephan Lany
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | | |
Collapse
|
48
|
Olejník K, Seifert T, Kašpar Z, Novák V, Wadley P, Campion RP, Baumgartner M, Gambardella P, Němec P, Wunderlich J, Sinova J, Kužel P, Müller M, Kampfrath T, Jungwirth T. Terahertz electrical writing speed in an antiferromagnetic memory. SCIENCE ADVANCES 2018; 4:eaar3566. [PMID: 29740601 PMCID: PMC5938222 DOI: 10.1126/sciadv.aar3566] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/08/2018] [Indexed: 05/08/2023]
Abstract
The speed of writing of state-of-the-art ferromagnetic memories is physically limited by an intrinsic gigahertz threshold. Recently, realization of memory devices based on antiferromagnets, in which spin directions periodically alternate from one atomic lattice site to the next has moved research in an alternative direction. We experimentally demonstrate at room temperature that the speed of reversible electrical writing in a memory device can be scaled up to terahertz using an antiferromagnet. A current-induced spin-torque mechanism is responsible for the switching in our memory devices throughout the 12-order-of-magnitude range of writing speeds from hertz to terahertz. Our work opens the path toward the development of memory-logic technology reaching the elusive terahertz band.
Collapse
Affiliation(s)
- Kamil Olejník
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- Corresponding author.
| | - Tom Seifert
- Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
| | - Zdeněk Kašpar
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
| | - Vít Novák
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - Peter Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - Richard P. Campion
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - Manuel Baumgartner
- Department of Materials, ETH Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland
| | - Pietro Gambardella
- Department of Materials, ETH Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland
| | - Petr Němec
- Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
| | - Joerg Wunderlich
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- Hitachi Cambridge Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Jairo Sinova
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55128 Mainz, Germany
| | - Petr Kužel
- Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Praha 8, Czech Republic
| | - Melanie Müller
- Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
| | - Tobias Kampfrath
- Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Tomas Jungwirth
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| |
Collapse
|
49
|
Hajiri T, Yoshida T, Filianina M, Jaiswal S, Borie B, Asano H, Zabel H, Kläui M. 45° sign switching of effective exchange bias due to competing anisotropies in fully epitaxial Co 3FeN/MnN bilayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:015806. [PMID: 29205170 DOI: 10.1088/1361-648x/aa9ba7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report an unusual angular-dependent exchange bias effect in ferromagnet/antiferromagnet bilayers, where both ferromagnet and antiferromagnet are epitaxially grown. Numerical model calculations predict an approximately 45° period for the sign switching of the exchange-bias field, depending on the ratio between magnetocrystalline anisotropy and exchange-coupling constant. The switching of the sign is indicative of a competition between a fourfold magnetocrystalline anisotropy of the ferromagnet and a unidirectional anisotropy field of the exchange coupling. This predicted unusual angular-dependent exchange bias and its magnetization switching process are confirmed by measurements on fully epitaxial Co3FeN/MnN bilayers by longitudinal and transverse magneto-optic Kerr effect magnetometry. These results provide a deeper understanding of the exchange coupling phenomena in fully epitaxial bilayers with tailored materials and open up a complex switching energy landscape engineering by anisotropies.
Collapse
Affiliation(s)
- T Hajiri
- Department of Materials Physics, Nagoya University, Nagoya 464-8603, Japan
| | | | | | | | | | | | | | | |
Collapse
|
50
|
Železný J, Zhang Y, Felser C, Yan B. Spin-Polarized Current in Noncollinear Antiferromagnets. PHYSICAL REVIEW LETTERS 2017; 119:187204. [PMID: 29219584 DOI: 10.1103/physrevlett.119.187204] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Indexed: 06/07/2023]
Abstract
Noncollinear antiferromagnets, such as Mn_{3}Sn and Mn_{3}Ir, were recently shown to be analogous to ferromagnets in that they have a large anomalous Hall effect. Here we show that these materials are similar to ferromagnets in another aspect: the charge current in these materials is spin polarized. In addition, we show that the same mechanism that leads to the spin-polarized current also leads to a transverse spin current, which has a distinct symmetry and origin from the conventional spin Hall effect. We illustrate the existence of the spin-polarized current and the transverse spin current by performing ab initio microscopic calculations and by analyzing the symmetry. We discuss possible applications of these novel spin currents, such as an antiferromagnetic metallic or tunneling junction.
Collapse
Affiliation(s)
- Jakub Železný
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Institute of Physics ASCR, 162 53 Praha 6, Czech Republic
| | - Yang Zhang
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Leibniz Institute for Solid State and Materials Research, 01069 Dresden, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Binghai Yan
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Department of Condensed Matter Physics, Weizmann Institute of Science, 7610001 Rehovot, Israel
| |
Collapse
|