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Meng X, Möller J, Menchón RE, Weismann A, Sánchez-Portal D, Garcia-Lekue A, Herges R, Berndt R. Kondo Effect of Co-Porphyrin: Remarkable Sensitivity to Adsorption Sites and Orientations. Nano Lett 2024; 24:180-186. [PMID: 38150551 DOI: 10.1021/acs.nanolett.3c03669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
We investigated the Kondo effect of cobalt(II)-5-15-bis(4'-bromophenyl)-10,20-bis(4'-iodophenyl)porphyrin (CoTPPBr2I2) molecules on Au(111) with low-temperature scanning tunneling microscopy under ultrahigh vacuum conditions. The molecules exhibit four adsorption configurations at the top and bridge sites of the surface with different molecular orientations. The Kondo resonance shows extraordinary sensitivity to the adsorption configuration. By switching the molecule between different configurations, the Kondo temperature is varied over a wide range from ≈8 up to ≈250 K. Density functional theory calculations reveal that changes of the adsorption configuration lead to distinct variations of the hybridization between the molecule and the surface. Furthermore, we show that surface reconstruction plays a significant role for the molecular Kondo effect.
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Affiliation(s)
- Xiangzhi Meng
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Jenny Möller
- Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Rodrigo E Menchón
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Facultad de Ciencias Exactas, Ingeniría y Agrimensura (FCEIA), Instituto de Física Rosario (IFIR), 2000 Rosario, Argentina
- Universidad Nacional de Rosario (UNR), 2000 Rosario, Argentina
| | - Alexander Weismann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Daniel Sánchez-Portal
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Centro de Física de Materiales CSIC-UPV/EHU, 20018 Donostia-San Sebastián, Spain
| | - Aran Garcia-Lekue
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Rainer Herges
- Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
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2
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Petrović J, Vrtnik S, Jelen A, Koželj P, Luzar J, Mihor P, Hu Q, Wencka M, Ambrožič B, Meden A, Dražić G, Guo S, Dolinšek J. The Kondo Effect in Ce xLaLuScY ( x = 0.05-1.0) High-Entropy Alloys. Materials (Basel) 2023; 16:7575. [PMID: 38138717 PMCID: PMC10744949 DOI: 10.3390/ma16247575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/04/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023]
Abstract
In the search for electronic phenomena in high-entropy alloys (HEAs) that go beyond the independent-electron description, we have synthesized a series of hexagonal rare earth (RE)-based HEAs: CexLaLuScY (x = 0.05-1.0). The measurements of electrical resistivity, magnetic susceptibility and specific heat have shown that the CexLaLuScY HEAs exhibit the Kondo effect, which is of a single impurity type in the entire range of employed Ce concentrations despite the alloys being classified as dense (concentrated) Kondo systems. A comparison to other known dense Kondo systems has revealed that the Kondo effect in the CexLaLuScY HEAs behaves quite differently from the chemically ordered Kondo lattices but quite similar to the RE-containing magnetic metallic glasses and randomly chemically disordered Kondo lattices of the chemical formula RE1xRE21-xM (with RE1 being magnetic and RE2 being nonmagnetic). The main reason for the similarity between HEAs and the metallic glasses and chemically disordered Kondo lattices appears to be the absence of a periodic 4f sublattice in these systems, which prevents the formation of a coherent state between the 4f-scattering sites in the T→ 0 limit. The crystal-glass duality of HEAs does not bring conceptually new features to the Kondo effect that would not be already present in other disordered dense Kondo systems. This study broadens the classification of HEAs to correlated electron systems.
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Affiliation(s)
- Julia Petrović
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | | | - Andreja Jelen
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Primož Koželj
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
| | - Jože Luzar
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Peter Mihor
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Qiang Hu
- Institute of Applied Physics, Jiangxi Academy of Sciences, Changdong Road 7777, Nanchang 330096, China
| | - Magdalena Wencka
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Bojan Ambrožič
- Center of Excellence in Nanoscience and Nanotechnology, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Anton Meden
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia
| | - Goran Dražić
- Department of Materials Chemistry, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
| | - Sheng Guo
- Industrial and Materials Science, Chalmers University of Technology, 41296 Göteborg, Sweden
| | - Janez Dolinšek
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
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3
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Roy N, Mahato PC, Saha S, Telling M, Lord JS, Adroja DT, Banerjee SS. Probing the strongly correlated magnetic state of Co 2C nanoparticles at low temperatures using μSR. J Phys Condens Matter 2023; 36:085603. [PMID: 37918015 DOI: 10.1088/1361-648x/ad08ec] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Accepted: 11/01/2023] [Indexed: 11/04/2023]
Abstract
Co2C nanoparticles (NPs) are amongst transition metal carbides whose magnetic properties have not been well explored. An earlier study (Royet al2021J. Phys.: Condens. Matter33375804) showed that a pellet made from Co2C NPs exhibits exchange bias (EB) effect below a temperature,TEB= 50 K and a spin glass (SG) feature emerges belowTSG= 5 K. In the current study we use magnetic, electrical transport, specific heat, and muon spin rotation (μSR) measurements to explore further the magnetic properties of a pellet made with 40 nm diameter pure Co2C NPs. We uncover the onset of Kondo localization at Kondo temperatureTK(= 40.1 K), which is close to the onset temperature (TEB) of the EB effect. A crossover from the Kondo-screened scenario to the Ruderman-Kittel-Kasuya-Yosida interaction-dominated regime is also observed forT
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Affiliation(s)
- Nirmal Roy
- Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - P C Mahato
- Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Suprotim Saha
- Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - M Telling
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot Oxon OX11 0QX, United Kingdom
| | - J S Lord
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot Oxon OX11 0QX, United Kingdom
| | - D T Adroja
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot Oxon OX11 0QX, United Kingdom
- Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa
| | - S S Banerjee
- Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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4
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Noei N, Mozara R, Montero AM, Brinker S, Ide N, Guimarães FSM, Lichtenstein AI, Berndt R, Lounis S, Weismann A. Manipulating the Spin Orientation of Co Atoms Using Monatomic Cu Chains. Nano Lett 2023; 23:8988-8994. [PMID: 37782684 DOI: 10.1021/acs.nanolett.3c02532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Harnessing the spin of single atoms is at the heart of quantum information nanotechnology based on magnetic concepts. By attaching single Co atoms to monatomic Cu chains, we demonstrate the ability to control the spin orientation by the atomic environment. Due to spin-orbit coupling (SOC), the spin is tilted by ≈58° from the surface normal toward the chain as evidenced by inelastic tunneling spectroscopy. These findings are reproduced by density functional theory calculations and have implications for Co atoms on pristine Cu(111), which are believed to be Kondo systems. Our quantum Monte Carlo calculations suggest that SOC suppresses the Kondo effect of Co atoms at chains and on the flat surface. Our work impacts the fundamental understanding of low-energy excitations in nanostructures on surfaces and demonstrates the ability to manipulate atomic-scale magnetic moments, which can have tremendous implications for quantum devices.
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Affiliation(s)
- Neda Noei
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Roberto Mozara
- Institut für Theoretische Physik, Universität Hamburg, 20355 Hamburg, Germany
| | - Ana M Montero
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
| | - Sascha Brinker
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
| | - Niklas Ide
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Filipe S M Guimarães
- Jülich Supercomputing Centre, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | | | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Samir Lounis
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
- Faculty of Physics, University of Duisburg-Essen and CENIDE, 47053 Duisburg, Germany
| | - Alexander Weismann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
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5
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Ara F, Fakruddin Shahed SM, Hossain MI, Katoh K, Yamashita M, Komeda T. Control of the Magnetic Interaction between Single-Molecule Magnet TbPc 2 and Superconductor NbSe 2 Surface by an Intercalated Co Atom. Nano Lett 2023; 23:6900-6906. [PMID: 37505070 DOI: 10.1021/acs.nanolett.3c01298] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
We demonstrate that an intercalated Co atom in superconductor NbSe2 could control the magnetic interaction between the adsorbed magnetic molecule of TbPc2 and the NbSe2 substrate. An intercalated Co atom enhances the magnetic interaction between the NbSe2 and the TbPc2 spin to cause Kondo resonance at the TbPc2 position, a spin-singlet state formed by the itinerary electron. By applying a surface-normal magnetic field, we change the molecule's spin direction from the initial one directed to the Co atom to the surface normal. The change appears as a split Kondo resonance at the TbPc2, one of which is enhanced at the Tb site, which disappears when the outer magnetic field normal to the surface is applied and never appears, even if we return B to 0 T. The phenomenon suggests that the intercalated magnetic atoms can control the magnetic interaction between a magnetic molecule and the superconductor NbSe2.
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Affiliation(s)
- Ferdous Ara
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai, Miyagi 980-8577, Japan
| | - Syed Mohammad Fakruddin Shahed
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai, Miyagi 980-8577, Japan
| | - Mohammad Ikram Hossain
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-Ku, Sendai, Miyagi 980-8578, Japan
| | - Keiichi Katoh
- Department of Chemistry, Graduate School of Science, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan
| | - Masahiro Yamashita
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-Ku, Sendai, Miyagi 980-8578, Japan
- School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Tadahiro Komeda
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai, Miyagi 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai, Miyagi 980-8577, Japan
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6
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Yamanaka S, Hikiji M, Michioka C, Ueda H, Yoshimura K. Magnetic properties induced by the Yb-valence inhomogeneity in the layered Kondo-lattice compound Yb 4RuGe 8. J Phys Condens Matter 2023. [PMID: 37253380 DOI: 10.1088/1361-648x/acda07] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have successfully grown single crystals of a novel ytterbium-based layered compound Yb4RuGe8and studied its structural, magnetic, thermal, and transport properties. The magnetic susceptibility has a broad peak caused by the Kondo effect at approximately 40 K and is enhanced below 15 K owing to the development of additional magnetic correlations. An analysis with the grand-Kadowaki-Woods relation reveals that the low-temperature state except for the effect of the additional magnetic correlations is a heavy-mass Fermi liquid. 
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Affiliation(s)
- Shunsuke Yamanaka
- Kyoto University Graduate School of Science Faculty of Science Department of Chemistry, Kyoto 606-8502, Japan, Kyoto, 606-8502, JAPAN
| | - Masahito Hikiji
- Kyoto University Graduate School of Science Faculty of Science Department of Chemistry, Kyoto 606-8502, Japan, Kyoto, 606-8502, JAPAN
| | - Chishiro Michioka
- Kyoto University Graduate School of Science Faculty of Science Department of Chemistry, Kyoto 606-8502, Japan, Kyoto, 606-8502, JAPAN
| | - Hiroaki Ueda
- Kyoto University Graduate School of Science Faculty of Science Department of Chemistry, Kyoto 606-8502, Japan, Kyoto, 606-8502, JAPAN
| | - Kazuyoshi Yoshimura
- Kyoto University Graduate School of Science Faculty of Science Department of Chemistry, Kyoto 606-8502, Japan, Kyoto, 606-8502, JAPAN
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7
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Valenta J, Tsujii N, Yamaoka H, Honda F, Hirose Y, Sakurai H, Terada N, Naka T, Nakane T, Koizumi T, Ishii H, Hiraoka N, Mori T. Unusually strong electronic correlation and field-induced ordered phase in YbCo 2. J Phys Condens Matter 2023; 35:285601. [PMID: 37015243 DOI: 10.1088/1361-648x/acca5a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 04/04/2023] [Indexed: 06/19/2023]
Abstract
We report the first study of electrical resistivity, magnetization, and specific heat on YbCo2. The measurements on a single-phased sample of YbCo2bring no evidence of magnetic ordering down to 0.3 K in a zero magnetic field. The manifestations of low Kondo temperature are observed. The specific heat value divided by temperature,C/T, keeps increasing logarithmically beyond 7 J/mol K2with decreasing temperature down to 0.3 K without no sign of magnetic ordering, suggesting a very large electronic specific heat. Analysis of the magnetic specific heat indicates that the large portion of the low-temperature specific heat is not explained simply by the low Kondo temperature but is due to the strong intersite magnetic correlation in both the 3dand 4felectrons. Temperature-dependent measurements under static magnetic fields up to 7 T are carried out, which show the evolution of field-induced transition above 2 T. The transition temperature increases with increasing field, pointing to a ferromagnetic character. The extrapolation of the transition temperature to zero field suggests that YbCo2is in the very proximity of the quantum critical point. These results indicate that in the unique case of YbCo2, the itinerant electron magnetism of Co 3d-electrons and the Kondo effect within the vicinity of quantum criticality of Yb 4f-local moments can both play a role.
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Affiliation(s)
- J Valenta
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
| | - N Tsujii
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
| | - H Yamaoka
- RIKEN Spring-8 Center, Sayo, Hyogo 679-5148, Japan
| | - F Honda
- Institute for Materials Research, Tohoku University, Ōarai, Ibaraki 311-1313, Japan
- Central Institute of Radioisotope Science and Safety, Kyushu University, Fukuoka 819-0395, Japan
| | - Y Hirose
- Department of Physics, Niigata University, Niigata 950-2181, Japan
| | - H Sakurai
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
| | - N Terada
- Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - T Naka
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
| | - T Nakane
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan
| | - T Koizumi
- Institute for Materials Research, Tohoku University, Ōarai, Ibaraki 311-1313, Japan
- Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan
| | - H Ishii
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - N Hiraoka
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - T Mori
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
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8
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Wang T, Luo X, Gao J, Jiang Z, Wang W, Yang X, Zhou N, Zhu X, Zhang L, Lu W, Song W, Lv H, Sun Y. Origin of the Anomalous Electrical Transport Behavior in Fe-Intercalated Weyl Semimetal T d -MoTe 2. Adv Mater 2023; 35:e2208800. [PMID: 36692248 DOI: 10.1002/adma.202208800] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Weyl semimetal Td -MoTe2 has recently attracted much attention due to its intriguing electronic properties and potential applications in spintronics. Here, Fe-intercalated Td -Fex MoTe2 single crystals (0 < x < 0.15 ) are grown successfully. The electrical and thermoelectric transport results consistently demonstrate that the phase transition temperature TS is gradually suppressed with increasing x. Theoretical calculation suggests that the increased energy of the Td phase, enhanced transition barrier, and more occupied bands in 1T' phase is responsible for the suppression in TS . In addition, a ρα -lnT behavior induced by Kondo effect is observed with x ≥ 0.08, due to the coupling between conduction carriers and the local magnetic moments of intercalated Fe atoms. For Td -Fe0.15 MoTe2 , a spin-glass transition occurs at ≈10 K. The calculated band structure of Td -Fe0.25 MoTe2 shows that two flat bands exist near the Fermi level, which are mainly contributed by the dyz and d x 2 - y 2 ${{\rm{d}}_{{x^2} - {y^2}}}$ orbitals of the Fe atoms. Finally, the electronic phase diagram of Td -Fex MoTe2 is established for the first time. This work provides a new route to control the structural instability and explore exotic electronic states for transition-metal dichalcogenides.
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Affiliation(s)
- Tianyang Wang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, 230026, China
| | - Xuan Luo
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Jingjing Gao
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, 230026, China
| | - Zhongzhu Jiang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, 230026, China
| | - Wei Wang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, 230026, China
| | - Xingcai Yang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei, 230026, China
| | - Nan Zhou
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Xiaoguang Zhu
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Lei Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Wenjian Lu
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Wenhai Song
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
| | - Hongyan Lv
- School of Physics, Hefei University of Technology, Hefei, 230009, China
| | - Yuping Sun
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, 230031, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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9
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Koikegami S. Pseudogap formation due to charge-transfer transition and Kondo effect. J Phys Condens Matter 2023; 35:185602. [PMID: 36848682 DOI: 10.1088/1361-648x/acbf95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
We investigate the doping evolution of the electronic state of the three-bandt-J-Umodel considering the normal state of the hole-doped high-Tcsuperconducting cuprate. In our model, when some number of holes are doped into the undoped state, thedelectron exhibits the charge-transfer (CT)-type Mott-Hubbard transition along with a chemical potential jump. A reduced CT gap is formed from thepband and the coherent component of thedband, and it shrinks due to charge fluctuations as more holes are doped as in the pseudogap (PG) phenomenon. This trend is reinforced as thed-pband hybridization is increased, and a Fermi liquid state is retrieved as in the Kondo effect. These suggest that the PG in the hole-doped cuprate emerges due to the CT transition and the Kondo effect.
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10
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Baum TY, Fernández S, Peña D, van der Zant HSJ. Magnetic Fingerprints in an All-Organic Radical Molecular Break Junction. Nano Lett 2022; 22:8086-8092. [PMID: 36206381 PMCID: PMC9614975 DOI: 10.1021/acs.nanolett.2c02326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 10/05/2022] [Indexed: 05/25/2023]
Abstract
Polycyclic aromatic hydrocarbons radicals are organic molecules with a nonzero total magnetic moment. Here, we report on charge-transport experiments with bianthracene-based radicals using a mechanically controlled break junction technique at low temperatures (6 K). The conductance spectra demonstrate that the magnetism of the diradical is preserved in solid-state devices and that it manifests itself either in the form of a Kondo resonance or inelastic electron tunneling spectroscopy signature caused by spin-flip processes. The magnetic fingerprints depend on the exact configuration of the molecule in the junction; this picture is supported by reference measurements on a radical molecule with the same backbone but with one free spin, in which only Kondo anomalies are observed. The results show that the open-shell structures based on the bianthracene core are interesting systems to study spin-spin interactions in solid-state devices, and this may open the way to control them either electrically or by mechanical strain.
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Affiliation(s)
- Thomas Y. Baum
- Kavli
Institute of Nanoscience, Delft University
of Technology, Lorentzweg 1, 2628 CJDelft, The Netherlands
| | - Saleta Fernández
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CiQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, Santiago
de Compostela, Spain15782
| | - Diego Peña
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CiQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, Santiago
de Compostela, Spain15782
| | - Herre S. J. van der Zant
- Kavli
Institute of Nanoscience, Delft University
of Technology, Lorentzweg 1, 2628 CJDelft, The Netherlands
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11
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Ma H, Qian Q, Qin B, Wan Z, Wu R, Zhao B, Zhang H, Zhang Z, Li J, Zhang Z, Li B, Wang L, Duan X. Controlled Synthesis of Ultrathin PtSe 2 Nanosheets with Thickness-Tunable Electrical and Magnetoelectrical Properties. Adv Sci (Weinh) 2022; 9:e2103507. [PMID: 34713628 PMCID: PMC8728827 DOI: 10.1002/advs.202103507] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 09/23/2021] [Indexed: 06/13/2023]
Abstract
Thickness-dependent chemical and physical properties have gained tremendous interest since the emergence of two-dimensional (2D) materials. Despite attractive prospects, the thickness-controlled synthesis of ultrathin nanosheets remains an outstanding challenge. Here, a chemical vapor deposition (CVD) route is reported to controllably synthesize high-quality PtSe2 nanosheets with tunable thickness and explore their thickness-dependent electronic and magnetotransport properties. Raman spectroscopic studies demonstrate all Eg , A1 g , A2 u , and Eu modes are red shift in thicker nanosheets. Electrical measurements demonstrate the 1.7 nm thick nanosheet is a semiconductor with room temperature field-effect mobility of 66 cm2 V-1 s-1 and on/off ratio of 106 . The 2.3-3.8 nm thick nanosheets show slightly gated modulation with high field-effect mobility up to 324 cm2 V-1 s-1 at room-temperature. When the thickness is over 3.8 nm, the nanosheets show metallic behavior with conductivity and breakdown current density up to 6.8 × 105 S m-1 and 6.9 × 107 A cm-2 , respectively. Interestingly, magnetoresistance (MR) studies reveal magnetic orders exist in this intrinsically non-magnetic material system, as manifested by the thickness-dependent Kondo effect, where both metal to insulator transition and negative MR appear upon cooling. Together, these studies suggest that PtSe2 is an intriguing system for both developing novel functional electronics and conducting fundamental 2D magnetism study.
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Affiliation(s)
- Huifang Ma
- Hunan Key Laboratory of Two-Dimensional Materials and State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China
- Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211800, China
| | - Qi Qian
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, 90095, United States
| | - Biao Qin
- Department of Applied Physics, School of Physics and Electronics, Hunan University, Changsha, 410082, China
| | - Zhong Wan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, 90095, United States
| | - Ruixia Wu
- Hunan Key Laboratory of Two-Dimensional Materials and State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China
| | - Bei Zhao
- Hunan Key Laboratory of Two-Dimensional Materials and State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China
| | - Hongmei Zhang
- Hunan Key Laboratory of Two-Dimensional Materials and State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China
| | - Zucheng Zhang
- Hunan Key Laboratory of Two-Dimensional Materials and State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China
| | - Jia Li
- Hunan Key Laboratory of Two-Dimensional Materials and State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China
| | - Zhengwei Zhang
- Hunan Key Laboratory of Two-Dimensional Materials and State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China
- School of Physics and Electronics, Central South University, Changsha, 410083, China
| | - Bo Li
- Department of Applied Physics, School of Physics and Electronics, Hunan University, Changsha, 410082, China
| | - Lin Wang
- Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211800, China
| | - Xidong Duan
- Hunan Key Laboratory of Two-Dimensional Materials and State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China
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12
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Florków P, Lipiński S. Impact of electron-phonon coupling on electron transport through T-shaped arrangements of quantum dots in the Kondo regime. Beilstein J Nanotechnol 2021; 12:1209-1225. [PMID: 34858774 PMCID: PMC8593695 DOI: 10.3762/bjnano.12.89] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/20/2021] [Indexed: 06/13/2023]
Abstract
We calculate the conductance through strongly correlated T-shaped molecular or quantum dot systems under the influence of phonons. The system is modelled by the extended Anderson-Holstein Hamiltonian. The finite-U mean-field slave boson approach is used to study many-body effects. Phonons influence both interference and correlations. Depending on the dot unperturbed energy and the strength of electron-phonon interaction, the system is occupied by a different number of electrons that effectively interact with each other repulsively or attractively. This leads, together with the interference effects, to different spin or charge Fano-Kondo effects.
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Affiliation(s)
- Patryk Florków
- Department of Theory of Nanostructures, Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Stanisław Lipiński
- Department of Theory of Nanostructures, Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland
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13
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Iorsh IV, Kibis OV. Optically induced Kondo effect in semiconductor quantum wells. J Phys Condens Matter 2021; 33:495302. [PMID: 34547723 DOI: 10.1088/1361-648x/ac28c2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
It is demonstrated theoretically that the circularly polarized irradiation of two-dimensional electron systems can induce the localized electron states which antiferromagnetically interact with conduction electrons, resulting in the Kondo effect. Conditions of experimental observation of the effect are discussed for semiconductor quantum wells.
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Affiliation(s)
- I V Iorsh
- Department of Physics and Engineering, ITMO University, Saint-Petersburg, 197101, Russia
- Department of Applied and Theoretical Physics, Novosibirsk State Technical University, Karl Marx Avenue 20, Novosibirsk 630073, Russia
| | - O V Kibis
- Department of Applied and Theoretical Physics, Novosibirsk State Technical University, Karl Marx Avenue 20, Novosibirsk 630073, Russia
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14
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Feng W, Hao Q, Chen Q, Qiu R, Lai X, Chen J, Liu Q. Comparative study of adsorptions, reactions and electronic properties of U atoms on Cu(111), Ag(111), Au(111) and Ru(0001) surfaces. Nanotechnology 2021; 32:425704. [PMID: 34256355 DOI: 10.1088/1361-6528/ac13e9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
The mysterious properties of individual U atoms on transition metal surfaces play indispensable parts in supplementing our understanding of uranium-transition metal systems, which are important subjects for both nuclear energy applications and fundamental scientific studies. By using scanning tunneling microscopy and density functional theory calculations, the adsorptions, reactions and electronic properties of individual U atoms on Cu(111), Ag(111), Au(111) and Ru(0001) surfaces were comparatively studied for the first time in this work. Upon the deposition of a small amount of U onto Cu(111) or Ag(111) at 8 K, individual U atoms show relatively high activity and can either be adsorbed on intact substrate surfaces or induce various surface vacancies surrounded by clusters of substrate atoms. By contrast, the majority of U atoms tend to dispersedly adsorb on intact surfaces of Au(111) and Ru(0001) rather than producing surface vacancies at the same temperature. In all cases, Kondo resonance manifested as asymmetric dip feature around Fermi energy is only observed in the differential tunneling conductance spectra of single U adatoms on Ag(111).
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Affiliation(s)
- Wei Feng
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang, Sichuan 621908, People's Republic of China
| | - Qunqing Hao
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang, Sichuan 621908, People's Republic of China
| | - Qiuyun Chen
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang, Sichuan 621908, People's Republic of China
| | - Ruizhi Qiu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang, Sichuan 621908, People's Republic of China
| | - Xinchun Lai
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang, Sichuan 621908, People's Republic of China
| | - Jinfan Chen
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang, Sichuan 621908, People's Republic of China
| | - Qin Liu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang, Sichuan 621908, People's Republic of China
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15
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Xu J, Zhu L, Gao H, Li C, Zhu MJ, Jia ZY, Zhu XY, Zhao Y, Li SC, Wu F, Shen Z. Ligand Non-innocence and Single Molecular Spintronic Properties of Ag II Dibenzocorrole Radical on Ag(111). Angew Chem Int Ed Engl 2021; 60:11702-11706. [PMID: 33694297 DOI: 10.1002/anie.202016674] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 03/09/2021] [Indexed: 11/08/2022]
Abstract
A facile method for the quantitative preparation of silver dibenzo-fused corrole Ag-1 is described. In contrast to the saddle conformation resolved by single-crystal X-ray analysis for Ag-1, it adopts an unprecedented domed geometry, with up and down orientations, when adsorbed on an Ag(111) surface. Sharp Kondo resonances near Fermi level, both at the corrole ligand and the silver center were observed by cryogenic STM, with relatively high Kondo temperature (172 K), providing evidence for a non-innocent AgII -corrole.2- species. Further investigation validates that benzene ring fusion and molecule-substrate interactions play pivotal roles in enhancing Ag(4d(x2 -y2 ))-corrole (π) orbital interactions, thereby stabilizing the open-shell singlet AgII -corrole.2- on Ag(111) surface. Moreover, this strategy used for constructing metal-free benzene-ring fused corrole ligand gives rise to inspiration of designing novel metal-corrole compound for multichannel molecular spintronics devices.
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Affiliation(s)
- Jialiang Xu
- State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210046, P. R. China
| | - Li Zhu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of, Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Hu Gao
- State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210046, P. R. China
| | - Chenhong Li
- State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210046, P. R. China
| | - Meng-Jiao Zhu
- State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210046, P. R. China
| | - Zhen-Yu Jia
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of, Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Xin-Yang Zhu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of, Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210046, P. R. China
| | - Shao-Chun Li
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of, Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.,Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University, Nanjing, 210093, China
| | - Fan Wu
- State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210046, P. R. China
| | - Zhen Shen
- State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210046, P. R. China
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16
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Dzsaber S, Yan X, Taupin M, Eguchi G, Prokofiev A, Shiroka T, Blaha P, Rubel O, Grefe SE, Lai HH, Si Q, Paschen S. Giant spontaneous Hall effect in a nonmagnetic Weyl-Kondo semimetal. Proc Natl Acad Sci U S A 2021; 118:e2013386118. [PMID: 33608457 DOI: 10.1073/pnas.2013386118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
States of matter are traditionally classified by their symmetry, as exemplified by the distinction between a solid and a liquid. Topological quantum phases, on the other hand, are harder to characterize, and still harder to identify. This is especially so in electronic systems with strong correlations. In this work, we uncover a purely electric-field-driven “giant” Hall response—orders of magnitude above expectation—in one such material and propose a mechanism whereby it is driven by strong correlations. Our results will enable the identification of electronic topological states in a broad range of strongly correlated quantum materials and may trigger efforts toward their exploitation in robust quantum electronics. Nontrivial topology in condensed-matter systems enriches quantum states of matter to go beyond either the classification into metals and insulators in terms of conventional band theory or that of symmetry-broken phases by Landau’s order parameter framework. So far, focus has been on weakly interacting systems, and little is known about the limit of strong electron correlations. Heavy fermion systems are a highly versatile platform to explore this regime. Here we report the discovery of a giant spontaneous Hall effect in the Kondo semimetal Ce3Bi4Pd3 that is noncentrosymmetric but preserves time-reversal symmetry. We attribute this finding to Weyl nodes—singularities of the Berry curvature—that emerge in the immediate vicinity of the Fermi level due to the Kondo interaction. We stress that this phenomenon is distinct from the previously detected anomalous Hall effect in materials with broken time-reversal symmetry; instead, it manifests an extreme topological response that requires a beyond-perturbation-theory description of the previously proposed nonlinear Hall effect. The large magnitude of the effect in even tiny electric and zero magnetic fields as well as its robust bulk nature may aid the exploitation in topological quantum devices.
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17
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Lee YL, Lee YW. Magnetic impurity in a triple-component semimetal. J Phys Condens Matter 2021; 33:135805. [PMID: 33434906 DOI: 10.1088/1361-648x/abdb11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/12/2021] [Indexed: 06/12/2023]
Abstract
We investigate the effects of a magnetic impurity in a multiband touching fermion system, specifically, a triple-component semimetal with a flat band, which can be realized in a family of transition metal silicides (CoSi family). When the chemical potential coincides with the flat band, it is expected that the impurity response of this system will be very different from that of an ordinary Dirac or Weyl semimetal of which the density of states at the Fermi level vanishes. We first determine the phase diagram within the mean-field approximation. Then, we study the local moment regime by employing two different methods. In the low temperature regime, the Kondo screening is analyzed by the variational wavefunction approach and the impurity contributions to the magnetic susceptibility and heat capacity are obtained, while at higher temperature, we use the equation of motion approach to calculate the occupation number of the impurity site and the impurity magnetic susceptibility. The results are compared and contrasted with those in the usual Fermi liquid and the Dirac/Weyl semimetals.
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Affiliation(s)
- Yu-Li Lee
- Department of Physics, National Changhua University of Education, Changhua, Taiwan, People's Republic of China
| | - Yu-Wen Lee
- Department of Applied Physics, Tunghai University, Taichung, Taiwan, People's Republic of China
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18
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López Antón R, Andrés JP, Ipatov M, González JA, González J, Zhukova V, Zhukov A. Magneto-Transport Properties of Co-Cu Thin Films Obtained by Co-Sputtering and Sputter Gas Aggregation. Nanomaterials (Basel) 2021; 11:nano11010134. [PMID: 33430007 PMCID: PMC7826580 DOI: 10.3390/nano11010134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/31/2020] [Accepted: 01/06/2021] [Indexed: 11/24/2022]
Abstract
Cu100−xCox thin films have been obtained by sputtering (x = 3, 9) and sputter gas aggregation (x = 2.5, 7.5) and subsequent annealing at 400 °C for 1 h. We have studied their structural, magnetic, and magnetotransport properties, both for the as-deposited and annealed samples, confirming the important role of the fabrication method in the properties. The magnetic measurements and the fitting of the hysteresis loops evidence that as-deposited samples consist of superparamagnetic (SPM) and/or ferromagnetic clusters, but in the samples obtained by gas aggregation the clusters are greater (with ferromagnetic behavior at room temperature) whereas in the samples obtained by sputtering, the clusters are smaller and there are also diluted Co atoms in the Cu matrix. The annealing affects negligibly the samples obtained by gas aggregation, but the ones obtained by sputtering are more affected, appearing greater clusters. This behavior is also reflected in the magnetoresistance (MR) measurements of the samples, with different shapes of the MR curves depending on the preparation method: more lineal in the whole range for sputtering, saturation at low fields (about 10 kOe) for gas aggregation. Finally, a Kondo-like minimum in the resistance versus temperature is found in the samples obtained by sputtering, affected by the magnetic field and the annealing. The observed Kondo-like behavior and the influence of annealing on a Kondo-like minimum in sputtered thin films have been attributed to the presence of diluted Co atoms in the Cu matrix and the Co precipitations from the Co–Cu solid solution upon annealing respectively.
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Affiliation(s)
- Ricardo López Antón
- Departament of Applied Physics, Instituto Regional de Investigación Científica Aplicada (IRICA), University of Castilla-La Mancha, 13071 Ciudad Real, Spain; (J.P.A.); (J.A.G.)
- Correspondence: ; Tel.: +34-926-295300 (ext. 3481)
| | - Juan Pedro Andrés
- Departament of Applied Physics, Instituto Regional de Investigación Científica Aplicada (IRICA), University of Castilla-La Mancha, 13071 Ciudad Real, Spain; (J.P.A.); (J.A.G.)
| | - Mihail Ipatov
- Departament of Advanced Polymers and Materials: Physics, Chemistry and Technology, Faculty of Chemistry, University of the Basque Country, 20018 San Sebastián, Spain; (M.I.); (J.G.); (V.Z.); (A.Z.)
- Department of Applied Physics I, EIG, University of the Basque Country, 20018 San Sebastián, Spain
| | - Juan Antonio González
- Departament of Applied Physics, Instituto Regional de Investigación Científica Aplicada (IRICA), University of Castilla-La Mancha, 13071 Ciudad Real, Spain; (J.P.A.); (J.A.G.)
| | - Julián González
- Departament of Advanced Polymers and Materials: Physics, Chemistry and Technology, Faculty of Chemistry, University of the Basque Country, 20018 San Sebastián, Spain; (M.I.); (J.G.); (V.Z.); (A.Z.)
| | - Valentina Zhukova
- Departament of Advanced Polymers and Materials: Physics, Chemistry and Technology, Faculty of Chemistry, University of the Basque Country, 20018 San Sebastián, Spain; (M.I.); (J.G.); (V.Z.); (A.Z.)
- Department of Applied Physics I, EIG, University of the Basque Country, 20018 San Sebastián, Spain
| | - Arcady Zhukov
- Departament of Advanced Polymers and Materials: Physics, Chemistry and Technology, Faculty of Chemistry, University of the Basque Country, 20018 San Sebastián, Spain; (M.I.); (J.G.); (V.Z.); (A.Z.)
- Department of Applied Physics I, EIG, University of the Basque Country, 20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
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19
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Ge J, Luo T, Lin Z, Shi J, Liu Y, Wang P, Zhang Y, Duan W, Wang J. Magnetic Moments Induced by Atomic Vacancies in Transition Metal Dichalcogenide Flakes. Adv Mater 2021; 33:e2005465. [PMID: 33306277 DOI: 10.1002/adma.202005465] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 11/19/2020] [Indexed: 06/12/2023]
Abstract
2D magnetism plays a key role in both fundamental physics and potential device applications. However, the instability of the discovered 2D magnetic materials has been one main obstacle in deep research and potential application of 2D magnetism. Here, a localized magnetic moment induced by Pt vacancies in air-stable type-II Dirac semimetal PtSe2 flakes is reported. The localized magnetic moments give rise to the Kondo effect, evidenced by logarithmic increment of resistance with decreasing temperature and isotropic negative longitudinal magnetoresistance. Additionally, the induced magnetic moment and Kondo temperature appear to depend on thickness in the thinner samples (<10 nm). The small magnetocrystalline anisotropy revealed by first-principles calculation indicates that the magnetic moments are randomly localized instead of long-range ordered. The findings demonstrate a new means to induce magnetism in 2D non-magnetic materials.
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Affiliation(s)
- Jun Ge
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Tianchuang Luo
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Zuzhang Lin
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Institute for Advanced Study, Tsinghua University, Beijing, 100084, China
| | - Jianping Shi
- The Institute for Advanced Studies, Wuhan University, Wuhan, 430072, China
| | - Yanzhao Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Pinyuan Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Yanfeng Zhang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, China
| | - Wenhui Duan
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- Institute for Advanced Study, Tsinghua University, Beijing, 100084, China
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100190, China
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
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20
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Florków P, Krychowski D, Lipiński S. Kondo effects in small-bandgap carbon nanotube quantum dots. Beilstein J Nanotechnol 2020; 11:1873-1890. [PMID: 33425637 PMCID: PMC7770385 DOI: 10.3762/bjnano.11.169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 12/03/2020] [Indexed: 06/12/2023]
Abstract
We study the magnetoconductance of small-bandgap carbon nanotube quantum dots in the presence of spin-orbit coupling in the strong-correlations regime. A finite-U slave-boson mean-field approach is used to study many-body effects. Different degeneracies are restored in a magnetic field and Kondo effects of different symmetries arise, including SU(3) effects of different types. Full spin-orbital degeneracy might be recovered at zero field and, correspondingly, the SU(4) Kondo effect sets in. We point out the possibility of the occurrence of electron-hole Kondo effects in slanting magnetic fields, which we predict to occur in magnetic fields with an orientation close to perpendicular. When the field approaches a transverse orientation a crossover from SU(2) or SU(3) symmetry into SU(4) is observed.
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Affiliation(s)
- Patryk Florków
- Department of Theory of Nanostructures, Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17,60-179 Poznań, Poland
| | - Damian Krychowski
- Department of Theory of Nanostructures, Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17,60-179 Poznań, Poland
| | - Stanisław Lipiński
- Department of Theory of Nanostructures, Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17,60-179 Poznań, Poland
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21
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Xu Z, Liu J, Hou S, Wang Y. Manipulation of Molecular Spin State on Surfaces Studied by Scanning Tunneling Microscopy. Nanomaterials (Basel) 2020; 10:E2393. [PMID: 33266045 DOI: 10.3390/nano10122393] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 11/27/2020] [Accepted: 11/27/2020] [Indexed: 11/17/2022]
Abstract
The adsorbed magnetic molecules with tunable spin states have drawn wide attention for their immense potential in the emerging fields of molecular spintronics and quantum computing. One of the key issues toward their application is the efficient controlling of their spin state. This review briefly summarizes the recent progress in the field of molecular spin state manipulation on surfaces. We focus on the molecular spins originated from the unpaired electrons of which the Kondo effect and spin excitation can be detected by scanning tunneling microscopy and spectroscopy (STM and STS). Studies of the molecular spin-carriers in three categories are overviewed, i.e., the ones solely composed of main group elements, the ones comprising 3d-metals, and the ones comprising 4f-metals. Several frequently used strategies for tuning molecular spin state are exemplified, including chemical reactions, reversible atomic/molecular chemisorption, and STM-tip manipulations. The summary of the successful case studies of molecular spin state manipulation may not only facilitate the fundamental understanding of molecular magnetism and spintronics but also inspire the design of the molecule-based spintronic devices and materials.
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22
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Hwang J, Lee S, Lee JE, Kang M, Ryu H, Joo HJ, Denlinger J, Park JH, Hwang C. Tunable Kondo Resonance at a Pristine Two-Dimensional Dirac Semimetal on a Kondo Insulator. Nano Lett 2020; 20:7973-7979. [PMID: 33104350 DOI: 10.1021/acs.nanolett.0c02751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The proximity of two different materials leads to an intricate coupling of quasiparticles so that an unprecedented electronic state is often realized at the interface. Here, we demonstrate a resonance-type many-body ground state in graphene, a nonmagnetic two-dimensional Dirac semimetal, when grown on SmB6, a Kondo insulator, via thermal decomposition of fullerene molecules. This ground state is typically observed in three-dimensional magnetic materials with correlated electrons. Above the characteristic Kondo temperature of the substrate, the electron band structure of pristine graphene remains almost intact. As temperature decreases, however, the Dirac Fermions of graphene become hybridized with the Sm 4f states. Remarkable enhancement of the hybridization and Kondo resonance is observed with further cooling and increasing charge-carrier density of graphene, evidencing the Kondo screening of the Sm 4f local magnetic moment by the conduction electrons of graphene at the interface. These findings manifest the realization of the Kondo effect in graphene by the proximity of SmB6 that is tuned by the temperature and charge-carrier density of graphene.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics, Pusan National University, Busan 46241, South Korea
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Seungseok Lee
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Division of Advanced Material Science, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Ji-Eun Lee
- Department of Physics, Pusan National University, Busan 46241, South Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Minhee Kang
- Department of Physics, Pusan National University, Busan 46241, South Korea
| | - Hyejin Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Hyun-Jeong Joo
- Department of Physics, Pusan National University, Busan 46241, South Korea
| | - Jonathan Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jae-Hoon Park
- Center for Complex Phase Materials, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, South Korea
- Division of Advanced Material Science, Pohang University of Science and Technology, Pohang 37673, South Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, South Korea
| | - Choongyu Hwang
- Department of Physics, Pusan National University, Busan 46241, South Korea
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23
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Abstract
A single molecule offers to tailor and control the probing capability of a scanning tunneling microscope when placed on the tip. With the help of first-principles calculations, we show that on-tip spin sensitivity is possible through the Kondo ground state of a spin S = 1/2 cobaltocene molecule. When attached to the tip apex, we observe a reproducible Kondo resonance, which splits apart upon tuning the exchange coupling of cobaltocene to an iron atom on the surface. The spin-split Kondo resonance provides quantitative information on the exchange field and on the spin polarization of the iron atom. We also demonstrate that molecular vibrations cause the emergence of Kondo side peaks, which, unlike the Kondo resonance, are sensitive to cobaltocene adsorption.
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Affiliation(s)
- Léo Garnier
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg F-67000, France
| | - Benjamin Verlhac
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg F-67000, France
| | - Paula Abufager
- Instituto de Física de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Universidad Nacional de Rosario, Avenida Pellegrini 250 (2000), Rosario 2000, Argentina
| | - Nicolás Lorente
- Centro de Física de Materiales (CFM), Donostia-San San Sebastián20018, Spain
- Donostia International Physics Center (DIPC), Donostia-San Sebastián20018, Spain
| | - Maider Ormaza
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg F-67000, France
| | - Laurent Limot
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg F-67000, France
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24
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Szlawska M, Gnida D, Ruszała P, Winiarski MJ, Samsel-Czekała M, Schmidt M, Grin Y, Kaczorowski D. Antiferromagnetic Ordering and Transport Anomalies in Single-Crystalline CeAgAs 2. Materials (Basel) 2020; 13:E3865. [PMID: 32882996 DOI: 10.3390/ma13173865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 11/16/2022]
Abstract
Single crystals of the ternary cerium arsenide CeAgAs2 were grown by chemical vapor transport. They were studied by means of x-ray diffraction, magnetization, heat capacity and electrical transport measurements. The experimental research was supplemented with electronic band structure calculations. The compound was confirmed to order antiferromagnetically at the Néel temperature of 4.9 K and to undergo metamagnetic transition in a field of 0.5 T at 1.72 K. The electrical resistivity shows distinct increase at low temperatures, which origin is discussed in terms of pseudo-gap formation in the density of states at the Fermi level and quantum corrections to the resistivity in the presence of atom disorder due to crystal structure imperfections.
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25
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Xu C, Liu Z, Zhang Z, Liu Z, Li J, Pan M, Kang N, Cheng HM, Ren W. Superhigh Uniform Magnetic Cr Substitution in a 2D Mo 2 C Superconductor for a Macroscopic-Scale Kondo Effect. Adv Mater 2020; 32:e2002825. [PMID: 32776372 DOI: 10.1002/adma.202002825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 06/27/2020] [Indexed: 06/11/2023]
Abstract
Substitutional doping provides an effective strategy to tailor the properties of 2D materials, but it remains an open challenge to achieve tunable uniform doping, especially at high doping level. Here, uniform lattice substitution of a 2D Mo2 C superconductor by magnetic Cr atoms with controlled concentration up to ≈46.9 at% by chemical vapor deposition and a specifically designed Cu/Cr/Mo trilayer growth substrate is reported. The concentration of Cr atoms can be easily tuned by simply changing the thickness of the Cr layer, and the samples retain the original structure of 2D Mo2 C even at a very high Cr concentration. The controlled uniform Cr doping enables the tuning of the competition of the 2D superconductor and the Kondo effect across the whole sample. Transport measurements show that with increasing Cr concentration, the superconductivity of the 2D Cr-doped Mo2 C crystals disappears along with the emergence of the Kondo effect, and the Kondo temperature increases monotonously. Using scanning tunneling microscopy/spectroscopy, the mechanism of the doping level effect on the interplay and evolution between superconductivity and the Kondo effect is revealed. This work paves a new way for the synthesis of 2D materials with widely tunable doping levels, and provides new understandings on the interplay between superconductivity and magnetism in the 2D limit.
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Affiliation(s)
- Chuan Xu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
| | - Zhen Liu
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing, 100871, P. R. China
| | - Zongyuan Zhang
- School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
- Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
| | - Zhibo Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
| | - Jingyin Li
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing, 100871, P. R. China
| | - Minghu Pan
- School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an, 710119, China
| | - Ning Kang
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing, 100871, P. R. China
| | - Hui-Ming Cheng
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, P. R. China
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, P. R. China
| | - Wencai Ren
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, P. R. China
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an, 710119, China
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26
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Sánchez D, Moskalets M. Quantum Transport in Mesoscopic Systems. Entropy (Basel) 2020; 22:E977. [PMID: 33286746 PMCID: PMC7597288 DOI: 10.3390/e22090977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 08/26/2020] [Accepted: 08/26/2020] [Indexed: 06/12/2023]
Abstract
Mesoscopic physics has become a mature field [...].
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Affiliation(s)
- David Sánchez
- Institute for Cross-Disciplinary Physics and Complex Systems IFISC (UIB-CSIC), E-07122 Palma de Mallorca, Spain
| | - Michael Moskalets
- Department of Metal and Semiconductor Physics, National Technical University “Kharkiv Polytechnic Institute”, 61002 Kharkiv, Ukraine
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27
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Lopes V, Martins GB, Manya MA, Anda EV. Kondo effect under the influence of spin-orbit coupling in a quantum wire. J Phys Condens Matter 2020; 32:435604. [PMID: 32647092 DOI: 10.1088/1361-648x/aba45c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/09/2020] [Indexed: 06/11/2023]
Abstract
The analysis of the impact of spin-orbit coupling (SOC) on the Kondo state has generated considerable controversy, mainly regarding the dependence of the Kondo temperatureTKon SOC strength. Here, we study the one-dimensional (1D) single impurity Anderson model (SIAM) subjected to Rashba (α) and Dresselhaus (β) SOC. It is shown that, due to time-reversal symmetry, the hybridization function between impurity and quantum wire is diagonal and spin independent (as it is the case for the zero-SOC SIAM), thus the finite-SOC SIAM has a Kondo ground state similar to that for the zero-SOC SIAM. This similarity allows the use of the Haldane expression forTK, with parameters renormalized by SOC, which are calculated through a physically motivated change of basis. Analytic results for the parameters of the SOC-renormalized Haldane expression are obtained, facilitating the analysis of the SOC effect overTK. It is found that SOC acting in the quantum wire exponentially decreasesTKwhile SOC at the impurity exponentially increases it. These analytical results are fully supported by calculations using the numerical renormalization group (NRG), applied to the wide-band regime, and the projector operator approach, applied to the infinite-Uregime. Literature results, using quantum Monte Carlo, for a system with Fermi energy near the bottom of the band, are qualitatively reproduced, using NRG. In addition, it is shown that the 1D SOC SIAM for arbitraryαandβdisplays a persistent spin helix SU(2) symmetry similar to the one for a 2D Fermi sea with the restrictionα=β.
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Affiliation(s)
- V Lopes
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Rio de Janeiro, 22453-900, Brazil
- Departamento de Física Aplicada, Universidad de Alicante, San Vicente del Raspeig, 03690, Alicante, Spain
| | - G B Martins
- Instituto de Física, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, 38400-902, Brazil
| | - M A Manya
- Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ, Brazil
| | - E V Anda
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Rio de Janeiro, 22453-900, Brazil
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28
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Kumari K, Sharma R, Singh N. A theory of resistivity in Kondo lattice materials: memory function approach. J Phys Condens Matter 2020; 32:425603. [PMID: 32634788 DOI: 10.1088/1361-648x/aba382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 07/07/2020] [Indexed: 06/11/2023]
Abstract
We have theoretically analysed DC resistivity (ρ) in the Kondo-lattice materials using the powerful memory function formalism. The complete temperature evolution ofρis investigated using the Wölfle-Götze expansion of the memory function. The resistivity in this model originates from spin-flip magnetic scattering of conductions-electron off the quasi-localizeddorfelectron spins. We find the famous resistivity upturn in lower temperature regime (kBT≪μd), whereμdis the effective chemical potential ofd-electrons. In the high temperature regime (μd≪kBT) we discover that resistivity scales as cube root ofT(ρ∝T32). Our results are in reasonable agreement with the experimental results reported in the literature.
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Affiliation(s)
- Komal Kumari
- Department of Physics, Himachal Pradesh University, Shimla, 171005, India
| | - Raman Sharma
- Department of Physics, Himachal Pradesh University, Shimla, 171005, India
| | - Navinder Singh
- Theoretical Physics Division, Physical Research Laboratory, Ahmedabad, 380009, India
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29
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Máthé L, Grosu I. Nonequilibrium Kondo effect in a graphene-coupled quantum dot in the presence of a magnetic field. Beilstein J Nanotechnol 2020; 11:225-239. [PMID: 32082962 PMCID: PMC7006482 DOI: 10.3762/bjnano.11.17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 12/11/2019] [Indexed: 06/01/2023]
Abstract
Background: Quantum dots connected to larger systems containing a continuum of states like charge reservoirs allow the theoretical study of many-body effects such as the Coulomb blockade and the Kondo effect. Results: Here, we analyze the nonequilibrium Kondo effect and transport phenomena in a quantum dot coupled to pure monolayer graphene electrodes under external magnetic fields for finite on-site Coulomb interaction. The system is described by the pseudogap Anderson Hamiltonian. We use the equation of motion technique to determine the retarded Green's function of the quantum dot. An analytical formula for the Kondo temperature is derived for electron and hole doping of the graphene leads. The Kondo temperature vanishes in the vicinity of the particle-hole symmetry point and at the Dirac point. In the case of particle-hole asymmetry, the Kondo temperature has a finite value even at the Dirac point. The influence of the on-site Coulomb interaction and the magnetic field on the transport properties of the system shows a tendency similar to the previous results obtained for quantum dots connected to metallic electrodes. Most remarkably, we find that the Kondo resonance does not show up in the density of states and in the differential conductance for zero chemical potential due to the linear energy dispersion of graphene. An analytical method to calculate self-energies is also developed which can be useful in the study of graphene-based systems. Conclusion: Our graphene-based quantum dot system provides a platform for potential applications of nanoelectronics. Furthermore, we also propose an experimental setup for performing measurements in order to verify our model.
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Affiliation(s)
- Levente Máthé
- Department of Molecular and Biomolecular Physics, National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donath, 400293 Cluj-Napoca, Romania
- Faculty of Physics, Babeş-Bolyai University, 1 Kogǎlniceanu, 400084 Cluj-Napoca, Romania
| | - Ioan Grosu
- Faculty of Physics, Babeş-Bolyai University, 1 Kogǎlniceanu, 400084 Cluj-Napoca, Romania
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30
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Liu H, Xue Y, Shi JA, Guzman RA, Zhang P, Zhou Z, He Y, Bian C, Wu L, Ma R, Chen J, Yan J, Yang H, Shen CM, Zhou W, Bao L, Gao HJ. Observation of the Kondo Effect in Multilayer Single-Crystalline VTe 2 Nanoplates. Nano Lett 2019; 19:8572-8580. [PMID: 31702927 DOI: 10.1021/acs.nanolett.9b03100] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report the chemical vapor deposition (CVD) growth, characterization, and low-temperature magnetotransport of 1T phase multilayer single-crystalline VTe2 nanoplates. The transport studies reveal that no sign of intrinsic long-range ferromagnetism but localized magnetic moments exist in the individual multilayer metallic VTe2 nanoplates. The localized moments give rise to the Kondo effect, evidenced by logarithmical increment of resistivity with decreasing temperature and negative magnetoresistance (NMR) regardless of the direction of magnetic field at temperatures below the resistivity minimum. The low-temperature resistivity upturn is well described by the Hamann equation, and the NMR at different temperatures, a manifestation of the magnetization of the localized spins, is well fitted to a Brillouin function for S = 1/2. Density functional theory calculations reveal that the localized magnetic moments mainly come from the interstitial vanadium ions in the VTe2 nanoplates. Our results will shed light on the study of magnetic properties, strong correlation, and many-body physics in two-dimensional metallic transition metal dichalcogenides.
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Affiliation(s)
- Hongtao Liu
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Yunzhou Xue
- College of Chemistry and Environmental Engineering , Shenzhen University , Shenzhen 518060 , P.R. China
| | - Jin-An Shi
- School of Physical Sciences and CAS Key Laboratory of Vacuum Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Roger A Guzman
- School of Physical Sciences and CAS Key Laboratory of Vacuum Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Panpan Zhang
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Zhang Zhou
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Yangu He
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
- Department of Physics, Applied Physics, and Astronomy , Rensselaer Polytechnic Institute , 110 Eighth Street , Troy , New York 12180 , United States
| | - Ce Bian
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Liangmei Wu
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Ruisong Ma
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Jiancui Chen
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Jiahao Yan
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Haitao Yang
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Cheng-Min Shen
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , P.R. China
| | - Wu Zhou
- School of Physical Sciences and CAS Key Laboratory of Vacuum Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Lihong Bao
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , P.R. China
| | - Hong-Jun Gao
- Institute of Physics & University of Chinese Academy of Sciences , Chinese Academy of Sciences , Beijing 100190 , P.R. China
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31
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Datta S, Weymann I, Płomińska A, Flahaut E, Marty L, Wernsdorfer W. Detection of Spin Reversal via Kondo Correlation in Hybrid Carbon Nanotube Quantum Dots. ACS Nano 2019; 13:10029-10035. [PMID: 31449383 DOI: 10.1021/acsnano.9b02091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We experimentally investigate the electronic transport through a double-wall carbon nanotube filled with Fe nanoparticles. At very low temperatures, the Kondo effect is observed between the confined electrons in the nanotube quantum dot and the delocalized electrons in the leads connecting the nanotube. We demonstrate that the presence of magnetic nanoparticles in the inner core of the nanotube results in a hysteretic behavior of the differential resistance of the system when the magnetic field is varied. This behavior is observed in the Kondo diamonds of the stability diagram, and the magnitude of hysteresis varies with the strength of the Kondo correlations in different diamonds. Our findings are corroborated with accurate numerical renormalization group calculations performed for an effective low-energy model involving fluctuations of the spin on the orbital level of the nanotube due to spin flips of the nanoparticles.
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Affiliation(s)
- Subhadeep Datta
- School of Physical Sciences , Indian Association for the Cultivation of Science , 2A & B Raja S. C. Mullick Road , Jadavpur, Kolkata 700032 , India
- Institut Néel , CNRS & Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 , France
| | - Ireneusz Weymann
- Faculty of Physics , Adam Mickiewicz University , ul. Uniwersytetu Poznańskiego 2 , 61-614 Poznań , Poland
| | - Anna Płomińska
- Faculty of Physics , Adam Mickiewicz University , ul. Uniwersytetu Poznańskiego 2 , 61-614 Poznań , Poland
| | - Emmanuel Flahaut
- CIRIMAT , Université de Toulouse , CNRS, INPT, UPS, UMR CNRS-UPS-INP No 5085, Université Toulouse 3 Paul Sabatier, Bât. CIRIMAT, 118, Route de Narbonne , 31062 Toulouse Cedex 9 , France
| | - Läetitia Marty
- Institut Néel , CNRS & Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 , France
| | - Wolfgang Wernsdorfer
- Institut Néel , CNRS & Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 , France
- Physikalisches Institut and Institute of Nanotechnology , Karlsruhe Institute of Technology , Wolfgang-Gaede-Strasse 1 , 76131 Karlsruhe , Germany
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32
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Xie L, Lin H, Zhang C, Li J, Merino-Díez N, Friedrich N, Bouju X, Li Y, Pascual JI, Xu W. Switching the Spin on a Ni Trimer within a Metal-Organic Motif by Controlling the On-Top Bromine Atom. ACS Nano 2019; 13:9936-9943. [PMID: 31381315 DOI: 10.1021/acsnano.9b04715] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Controlling the spin of metal atoms embedded in molecular systems is a key step toward the realization of molecular electronics and spintronics. Many efforts have been devoted to explore the influencing factors dictating the survival or quenching of a magnetic moment in a metal-organic molecule, and among others, the spin control by axial ligand attachments is the most promising. Herein, from the interplay of high-resolution scanning tunneling microscopy imaging/manipulation and scanning tunneling spectroscopy measurements together with density functional theory calculations, we successfully demonstrate that a Ni trimer within a metal-organic motif acquires a net spin promoted by the adsorption of an on-top Br atom. The spin localization in the trimetal centers bonded to Br was monitored via the Kondo effect. The removal of the Br ligand resulted in the switch from a Kondo ON to a Kondo OFF state. The magnetic state induced by the Br ligand is theoretically attributed to the enhanced Br 4pz and Ni 3dz2 states due to the charge redistribution. The manipulation strategy reported here provides the possibility to explore potential applications of spin-tunable structures in spintronic devices.
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Affiliation(s)
- Lei Xie
- Interdisciplinary Materials Research Center, College of Materials Science and Engineering , Tongji University , Shanghai 201804 , People's Republic of China
| | - Haiping Lin
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices , Soochow University , 199 Ren'ai Road , Suzhou 215123 , Jiangsu , People's Republic of China
| | - Chi Zhang
- Interdisciplinary Materials Research Center, College of Materials Science and Engineering , Tongji University , Shanghai 201804 , People's Republic of China
| | - Jingcheng Li
- CIC nanoGUNE , 20018 San Sebastián-Donostia , Spain
| | - Nestor Merino-Díez
- CIC nanoGUNE , 20018 San Sebastián-Donostia , Spain
- Donostia International Physics Center (DIPC) , 20018 San Sebastián-Donostia , Spain
| | | | - Xavier Bouju
- CEMES-CNRS, Université de Toulouse , 31000 Toulouse , France
| | - Youyong Li
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices , Soochow University , 199 Ren'ai Road , Suzhou 215123 , Jiangsu , People's Republic of China
| | - Jose Ignacio Pascual
- CIC nanoGUNE , 20018 San Sebastián-Donostia , Spain
- Ikerbasque, Basque Foundation for Science , 48013 Bilbao , Spain
| | - Wei Xu
- Interdisciplinary Materials Research Center, College of Materials Science and Engineering , Tongji University , Shanghai 201804 , People's Republic of China
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Abstract
LaNiO3/SrIrO3 (LNO/SIO) heterostructures were deposited epitaxially on (001) SrTiO3 substrates. Transport characteristics of these LNO/SIO heterostructures were investigated as functions of LNO and SIO thickness. It has been observed that interfacing with SIO induces a metal-insulator transition at about 20 K in a 10 unit cell thick LNO film, which is otherwise metallic down to 2 K. In addition, this metal-insulator transition is irrelevant to the thickness of SIO, indicative of an interfacial effect. X-ray absorption measurements reveal an electron transfer from LNO to SIO across the interface. Meanwhile, the observation of a spin-glass-like state manifests the importance of spin-dependent scattering. The metal-insulator transition is discussed in terms of Kondo effect by random scattering from impurity spins associated with the interfacial electron transfer and the Dzyaloshinskii-Moriya interaction due to strong spin-orbit coupling inherent in 5d perovskite SIO.
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34
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Dutta B, Majidi D, García Corral A, Erdman PA, Florens S, Costi TA, Courtois H, Winkelmann CB. Direct Probe of the Seebeck Coefficient in a Kondo-Correlated Single-Quantum-Dot Transistor. Nano Lett 2019; 19:506-511. [PMID: 30566839 DOI: 10.1021/acs.nanolett.8b04398] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report on the first measurement of the Seebeck coefficient in a tunnel-contacted and gate-tunable individual single-quantum dot junction in the Kondo regime, fabricated using the electromigration technique. This fundamental thermoelectric parameter is obtained by directly monitoring the magnitude of the voltage induced in response to a temperature difference across the junction, while keeping a zero net tunneling current through the device. In contrast to bulk materials and single molecules probed in a scanning tunneling microscopy (STM) configuration, investigating the thermopower in nanoscale electronic transistors benefits from the electric tunability to showcase prominent quantum effects. Here, striking sign changes of the Seebeck coefficient are induced by varying the temperature, depending on the spin configuration in the quantum dot. The comparison with numerical renormalization group (NRG) calculations demonstrates that the tunneling density of states is generically asymmetric around the Fermi level in the leads, both in the cotunneling and Kondo regimes.
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Affiliation(s)
- Bivas Dutta
- Université Grenoble Alpes, CNRS, Grenoble INP*, Institut Néel , 38000 Grenoble , France
| | - Danial Majidi
- Université Grenoble Alpes, CNRS, Grenoble INP*, Institut Néel , 38000 Grenoble , France
| | - Alvaro García Corral
- Université Grenoble Alpes, CNRS, Grenoble INP*, Institut Néel , 38000 Grenoble , France
| | - Paolo A Erdman
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR , 56127 Pisa , Italy
| | - Serge Florens
- Université Grenoble Alpes, CNRS, Grenoble INP*, Institut Néel , 38000 Grenoble , France
| | - Theo A Costi
- Peter Grünberg Institut , Forschungszentrum Jülich , 52425 Jülich , Germany
| | - Hervé Courtois
- Université Grenoble Alpes, CNRS, Grenoble INP*, Institut Néel , 38000 Grenoble , France
| | - Clemens B Winkelmann
- Université Grenoble Alpes, CNRS, Grenoble INP*, Institut Néel , 38000 Grenoble , France
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35
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Hwang J, Kim K, Ryu H, Kim J, Lee JE, Kim S, Kang M, Park BG, Lanzara A, Chung J, Mo SK, Denlinger J, Min BI, Hwang C. Emergence of Kondo Resonance in Graphene Intercalated with Cerium. Nano Lett 2018; 18:3661-3666. [PMID: 29761696 DOI: 10.1021/acs.nanolett.8b00784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interaction between a magnetic impurity, such as cerium (Ce) atom, and surrounding electrons has been one of the core problems in understanding many-body interaction in solid and its relation to magnetism. Kondo effect, the formation of a new resonant ground state with quenched magnetic moment, provides a general framework to describe many-body interaction in the presence of magnetic impurity. In this Letter, a combined study of angle-resolved photoemission (ARPES) and dynamic mean-field theory (DMFT) on Ce-intercalated graphene shows that Ce-induced localized states near Fermi energy, EF, hybridized with the graphene π-band, exhibit gradual increase in spectral weight upon decreasing temperature. The observed temperature dependence follows the expectations from the Kondo picture in the weak coupling limit. Our results provide a novel insight how Kondo physics emerges in the sea of two-dimensional Dirac electrons.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Kyoo Kim
- Max Planck-POSTECH/Hsinchu Center for Complex Phase Materials , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Hyejin Ryu
- Department of Physics , Pusan National University , Busan 46241 , Korea
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Center for Spintronics , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Jingul Kim
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Ji-Eun Lee
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Sooran Kim
- Max Planck-POSTECH/Hsinchu Center for Complex Phase Materials , Pohang University of Science and Technology , Pohang 37673 , Korea
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Minhee Kang
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Byeong-Gyu Park
- Pohang Accelerator Laboratory , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Alessandra Lanzara
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Department of Physics , University of California , Berkeley , California 94720 , United States
| | - Jinwook Chung
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
- Department of Physics and Photon Science , Gwangju Institute of Science and Technology , Gwangju 61005 , Korea
| | - Sung-Kwan Mo
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Jonathan Denlinger
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Byung Il Min
- Department of Physics , Pohang University of Science and Technology , Pohang 37673 , Korea
| | - Choongyu Hwang
- Department of Physics , Pusan National University , Busan 46241 , Korea
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36
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Chen J, Isshiki H, Baretzky C, Balashov T, Wulfhekel W. Abrupt Switching of Crystal Fields during Formation of Molecular Contacts. ACS Nano 2018; 12:3280-3286. [PMID: 29565560 DOI: 10.1021/acsnano.7b07927] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Magnetic molecules have the potential to be used as building blocks for bits in quantum computers. The spin states of the magnetic ion in the molecule can be represented by the effective spin Hamiltonian describing the zero field splitting (ZFS) of the magnetic states. We determined the ZFS of mechanically flexible metal-chelate molecules (Co, Ni, and Cu as metal ions) adsorbed on Cu2N/Cu(100) by inelastic tunneling spectroscopy at temperatures down to 30 mK. When moving the tip toward the molecule, the tunneling current abruptly jumps to higher values, indicating the sudden deformation of the molecule bridging the tunneling junction. Hand in hand with the formation of the contact, an abrupt change of the ZFS occurs. This work also implies that ZFS expected in mechanical break junctions can drastically deviate from that of adsorbed molecules probed by other techniques.
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Affiliation(s)
- Jinjie Chen
- Physikalisches Institut , Karlsruhe Institute of Technology (KIT) , Wolfgang-Gaede-Straße 1 , 76131 Karlsruhe , Germany
| | - Hironari Isshiki
- Physikalisches Institut , Karlsruhe Institute of Technology (KIT) , Wolfgang-Gaede-Straße 1 , 76131 Karlsruhe , Germany
| | - Clemens Baretzky
- Physikalisches Institut , Karlsruhe Institute of Technology (KIT) , Wolfgang-Gaede-Straße 1 , 76131 Karlsruhe , Germany
| | - Timofey Balashov
- Physikalisches Institut , Karlsruhe Institute of Technology (KIT) , Wolfgang-Gaede-Straße 1 , 76131 Karlsruhe , Germany
| | - Wulf Wulfhekel
- Physikalisches Institut , Karlsruhe Institute of Technology (KIT) , Wolfgang-Gaede-Straße 1 , 76131 Karlsruhe , Germany
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Abstract
While electronic states with nontrivial topology have traditionally been known in insulators, they have been evidenced in metals during the past 2 years. Such Weyl semimetals show topological protection while conducting electricity both in the bulk and on the surface. An outstanding question is whether topological protection can happen in metals with strong correlations. Here, we report theoretical work on a strongly correlated lattice model to demonstrate the emergence of a Weyl–Kondo semimetal. We identify Weyl fermions in the bulk and Fermi arcs on the surface, both of which are associated with the many-body phenomenon called the Kondo effect. We determine a key signature of this Weyl–Kondo semimetal, which is realized in a recently discovered heavy-fermion compound. Insulating states can be topologically nontrivial, a well-established notion that is exemplified by the quantum Hall effect and topological insulators. By contrast, topological metals have not been experimentally evidenced until recently. In systems with strong correlations, they have yet to be identified. Heavy-fermion semimetals are a prototype of strongly correlated systems and, given their strong spin-orbit coupling, present a natural setting to make progress. Here, we advance a Weyl–Kondo semimetal phase in a periodic Anderson model on a noncentrosymmetric lattice. The quasiparticles near the Weyl nodes develop out of the Kondo effect, as do the surface states that feature Fermi arcs. We determine the key signatures of this phase, which are realized in the heavy-fermion semimetal Ce3Bi4Pd3. Our findings provide the much-needed theoretical foundation for the experimental search of topological metals with strong correlations and open up an avenue for systematic studies of such quantum phases that naturally entangle multiple degrees of freedom.
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38
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Amokrane A, Klyatskaya S, Boero M, Ruben M, Bucher JP. Role of π-Radicals in the Spin Connectivity of Clusters and Networks of Tb Double-Decker Single Molecule Magnets. ACS Nano 2017; 11:10750-10760. [PMID: 28967736 DOI: 10.1021/acsnano.7b05804] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
When single molecule magnets (SMMs) self-assemble into 2D networks on a surface, they interact via the π-electrons of their ligands. This interaction is relevant to the quantum entanglement between molecular qubits, a key issue in quantum computing. Here, we examine the role played by the unpaired radical electron in the top ligand of Tb double-decker SMMs by comparing the spectroscopic features of isolated and 2D assembled entities on surfaces. High-resolution scanning tunneling microscopy (STM) is used to evidence experimentally the Kondo resonance of the unpaired radical spins in clusters and islands and its quenching due to up-pairing at orbital overlaps. The presence or the absence of the Kondo feature in the dI/dV maps turns out to be a good measure of the lateral interaction between molecules in 2D networks. In a 2D cluster of molecules, the π-orbital lobes that are linked through the orbital overlap show paired-up electron wave function (one singly occupied molecular orbital (SOMO) with spin-up and the other with spin-down) and therefore do not experience the Kondo resonance in the experiment. As a result, small clusters built by STM-assisted manipulation of molecules show alternating Kondo features of quantum mechanical origin, from the monomer to the dimer and the trimer. On the other hand, when the TbPc2 molecular clusters grow larger and form extended domains, a geometric rearrangement occurs, leading to the quenching of the Kondo signal on one lobe out of two. The even distribution of overlapping (SOMO) lobes on the perimeter of the molecule is induced by the square symmetry of the semi-infinite lattice and clearly distinguishes the lattice from the clusters.
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Affiliation(s)
- Anis Amokrane
- Université de Strasbourg , CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France
| | - Svetlana Klyatskaya
- Karlsruher Institut für Technologie , Institut für Nanotechnologie, D-76344 Eggenstein-Leopoldshafen, Germany
| | - Mauro Boero
- Université de Strasbourg , CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France
| | - Mario Ruben
- Karlsruher Institut für Technologie , Institut für Nanotechnologie, D-76344 Eggenstein-Leopoldshafen, Germany
| | - Jean-Pierre Bucher
- Université de Strasbourg , CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France
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39
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Yan H, Zhang Z, Wang S, Zhang H, Chen C, Jin K. Modulated Transport Behavior of Two-Dimensional Electron Gas at Ni-Doped LaAlO 3/SrTiO 3 Heterointerfaces. ACS Appl Mater Interfaces 2017; 9:39011-39017. [PMID: 29034682 DOI: 10.1021/acsami.7b11727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Modulating transport behaviors of two-dimensional electron gases are of critical importance for applications of the next-generation multifunctional oxide electronics. In this study, transport behaviors of LaAlO3/SrTiO3 heterointerfaces modified through the Ni dopant and the light irradiation have been investigated. Through the Ni dopant, the resistances increase significantly and a resistance upturn phenomenon due to the Kondo effect is observed at T < 40 K. Under a 360 nm light irradiation, the interfaces exhibit a persistent photoconductivity and a suppressed Kondo effect at low temperature due to the increased mobility measured through the photo-Hall method. Moreover, the relative changes in resistance of interfaces induced by light are increased from 800 to 6600% at T = 12 K with increasing the substitution of Ni, which is discussed by the band bending and the lattice effect due to the Ni dopant. This work paves the way for better controlling the emerging properties of complex oxide heterointerfaces and would be helpful for photoelectric device applications based on all-oxides.
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Affiliation(s)
- Hong Yan
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science, Northwestern Polytechnical University , Xi'an 710072, China
| | - Zhaoting Zhang
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science, Northwestern Polytechnical University , Xi'an 710072, China
| | - Shuanhu Wang
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science, Northwestern Polytechnical University , Xi'an 710072, China
| | - Hongrui Zhang
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science, Northwestern Polytechnical University , Xi'an 710072, China
| | - Changle Chen
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science, Northwestern Polytechnical University , Xi'an 710072, China
| | - Kexin Jin
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science, Northwestern Polytechnical University , Xi'an 710072, China
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40
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Choi DJ, Robles R, Yan S, Burgess JAJ, Rolf-Pissarczyk S, Gauyacq JP, Lorente N, Ternes M, Loth S. Building Complex Kondo Impurities by Manipulating Entangled Spin Chains. Nano Lett 2017; 17:6203-6209. [PMID: 28872317 DOI: 10.1021/acs.nanolett.7b02882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The creation of molecule-like structures in which magnetic atoms interact controllably is full of potential for the study of complex or strongly correlated systems. Here, we create spin chains in which a strongly correlated Kondo state emerges from magnetic coupling of transition-metal atoms. We build chains up to ten atoms in length by placing Fe and Mn atoms on a Cu2N surface with a scanning tunneling microscope. The atoms couple antiferromagnetically via superexchange interaction through the nitrogen atom network of the surface. The emergent Kondo resonance is spatially distributed along the chain. Its strength can be controlled by mixing atoms of different transition metal elements and manipulating their spatial distribution. We show that the Kondo screening of the full chain by the electrons of the nonmagnetic substrate depends on the interatomic entanglement of the spins in the chain, demonstrating the prerequisites to build and probe spatially extended strongly correlated nanostructures.
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Affiliation(s)
- Deung-Jang Choi
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Roberto Robles
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology , Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Shichao Yan
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Jacob A J Burgess
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Steffen Rolf-Pissarczyk
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Jean-Pierre Gauyacq
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay , Bât. 351, 91405 Orsay Cedex, France
| | - Nicolás Lorente
- Centro de Física de Materiales, CFM/MPC (CSIC-UPV/EHU) , Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - Markus Ternes
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Sebastian Loth
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart , Pfaffenwaldring 57, 70569 Stuttgart, Germany
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41
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Kumar A, Banerjee K, Dvorak M, Schulz F, Harju A, Rinke P, Liljeroth P. Charge-Transfer-Driven Nonplanar Adsorption of F 4TCNQ Molecules on Epitaxial Graphene. ACS Nano 2017; 11:4960-4968. [PMID: 28467831 DOI: 10.1021/acsnano.7b01599] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
π-conjugated organic molecules tend to adsorb in a planar configuration on graphene irrespective of their charge state. In contrast, here we demonstrate charging-induced strong structural relaxation of tetrafluorotetracyanoquinodimethane (F4TCNQ) on epitaxial graphene on Ir(111) (G/Ir(111)). The work function modulation over the graphene moiré unit cell causes site-selective charging of F4TCNQ. Upon charging, the molecule anchors to the face-centered cubic sites of the G/Ir(111) moiré through one or two cyano groups. The reaction is reversible and can be triggered on a single molecule by moving it between different adsorption sites. We introduce a model taking into account the trade-off between tilt-induced charging and reduced van der Waals interactions, which provides a general framework for understanding charging-induced structural relaxation on weakly interacting substrates. In addition, we argue that the partial sp3 rehybridization of the underlying graphene and the possible bonding mechanism between the cyano groups and the graphene substrate are also relevant for the complete understanding of the experiments. These results provide insight into molecular charging on graphene, and they are directly relevant for potential device applications where the use of molecules has been suggested for doping and band structure engineering.
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Affiliation(s)
- Avijit Kumar
- Department of Applied Physics and ‡COMP/Department of Applied Physics, Aalto University School of Science , 00076 Aalto, Finland
| | - Kaustuv Banerjee
- Department of Applied Physics and ‡COMP/Department of Applied Physics, Aalto University School of Science , 00076 Aalto, Finland
| | - Marc Dvorak
- Department of Applied Physics and ‡COMP/Department of Applied Physics, Aalto University School of Science , 00076 Aalto, Finland
| | - Fabian Schulz
- Department of Applied Physics and ‡COMP/Department of Applied Physics, Aalto University School of Science , 00076 Aalto, Finland
| | - Ari Harju
- Department of Applied Physics and ‡COMP/Department of Applied Physics, Aalto University School of Science , 00076 Aalto, Finland
| | - Patrick Rinke
- Department of Applied Physics and ‡COMP/Department of Applied Physics, Aalto University School of Science , 00076 Aalto, Finland
| | - Peter Liljeroth
- Department of Applied Physics and ‡COMP/Department of Applied Physics, Aalto University School of Science , 00076 Aalto, Finland
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42
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Jacobson P, Muenks M, Laskin G, Brovko O, Stepanyuk V, Ternes M, Kern K. Potential energy-driven spin manipulation via a controllable hydrogen ligand. Sci Adv 2017; 3:e1602060. [PMID: 28439541 PMCID: PMC5392040 DOI: 10.1126/sciadv.1602060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 02/19/2017] [Indexed: 05/30/2023]
Abstract
Spin-bearing molecules can be stabilized on surfaces and in junctions with desirable properties, such as a net spin that can be adjusted by external stimuli. Using scanning probes, initial and final spin states can be deduced from topographic or spectroscopic data, but how the system transitions between these states is largely unknown. We address this question by manipulating the total spin of magnetic cobalt hydride complexes on a corrugated boron nitride surface with a hydrogen-functionalized scanning probe tip by simultaneously tracking force and conductance. When the additional hydrogen ligand is brought close to the cobalt monohydride, switching between a correlated S = 1/2 Kondo state, where host electrons screen the magnetic moment, and an S = 1 state with magnetocrystalline anisotropy is observed. We show that the total spin changes when the system is transferred onto a new potential energy surface that is defined by the position of the hydrogen in the junction. These results show how and why chemically functionalized tips are an effective tool to manipulate adatoms and molecules and a promising new method to selectively tune spin systems.
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Affiliation(s)
- Peter Jacobson
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - Matthias Muenks
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - Gennadii Laskin
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - Oleg Brovko
- Abdus Salam International Centre for Theoretical Physics, Trieste, Italy
| | - Valeri Stepanyuk
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Markus Ternes
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - Klaus Kern
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
- Institut de Physique, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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43
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Pacchioni GE, Pivetta M, Gragnaniello L, Donati F, Autès G, Yazyev OV, Rusponi S, Brune H. Two-Orbital Kondo Screening in a Self-Assembled Metal-Organic Complex. ACS Nano 2017; 11:2675-2681. [PMID: 28234448 DOI: 10.1021/acsnano.6b07431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Iron atoms adsorbed on a Cu(111) surface and buried under polyphenyl dicarbonitrile molecules exhibit strongly spatial anisotropic Kondo features with directionally dependent Kondo temperatures and line shapes, as evidenced by scanning tunneling spectroscopy. First-principles calculations find nearly full polarization for the half-filled Fe 3dxz and 3dyz orbitals, which therefore can give rise to Kondo screening with the experimentally observed directional dependence and distinct Kondo temperatures. X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements confirm that the spin in both channels is effectively Kondo-screened. At ideal Fe coverage, these two-orbital Kondo impurities are arranged in a self-assembled honeycomb superlattice.
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Affiliation(s)
- Giulia E Pacchioni
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Marina Pivetta
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Luca Gragnaniello
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Fabio Donati
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Gabriel Autès
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Oleg V Yazyev
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Stefano Rusponi
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Harald Brune
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
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44
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Choi DJ, Guissart S, Ormaza M, Bachellier N, Bengone O, Simon P, Limot L. Kondo Resonance of a Co Atom Exchange Coupled to a Ferromagnetic Tip. Nano Lett 2016; 16:6298-6302. [PMID: 27598512 DOI: 10.1021/acs.nanolett.6b02617] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Kondo effect of a Co atom on Cu(100) was investigated with a low-temperature scanning tunneling microscope using a monoatomically sharp nickel tip. Upon a tip-Co contact, the differential conductance spectra exhibit a spin-split asymmetric Kondo resonance. The computed ab initio value of the exchange coupling is too small to suppress the Kondo effect, but sufficiently large to produce the splitting observed. A quantitative analysis of the line shape using the numerical renormalization group technique indicates that the junction spin polarization is weak.
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Affiliation(s)
- D-J Choi
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
- CIC nanoGUNE , 20018 Donostia-San Sebastián, Spain
| | - S Guissart
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud 11 , 91405 Orsay, France
| | - M Ormaza
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
| | - N Bachellier
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
| | - O Bengone
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
| | - P Simon
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud 11 , 91405 Orsay, France
| | - L Limot
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
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45
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Zheng C, Shull RD, Chen PJ, Pong PWT. Kondo Effect in Magnetic Tunnel Junctions with an AlO x Tunnel Barrier. Phys Lett A 2016; 380:2237-2241. [PMID: 28690361 PMCID: PMC5497476 DOI: 10.1016/j.physleta.2016.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The influence of the magnetization configuration on Kondo effect in magnetic tunnel junction is investigated. In the parallel configuration, an additional resistance contribution (R*) below 40 K exhibits a logarithmic temperature dependence, indicating the presence of Kondo effect. However, in the anti-parallel configuration, the Kondo-effect-associated spin-flip scattering has a nontrivial contribution to the tunneling current, which compensates the reduction of the current directly caused by Kondo scattering, making R* disappear. These results indicate that suppression and restoration of Kondo effect can be experimentally achieved by altering the magnetization configuration, enhancing our understanding of the role of Kondo effect in spin-dependent transport.
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Affiliation(s)
- Chao Zheng
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong
| | - Robert D. Shull
- Functional Nanostructured Materials Group, National Institute of Standards and Technology, Gaithersburg, MD 20899–8552, United States
| | - P. J. Chen
- Functional Nanostructured Materials Group, National Institute of Standards and Technology, Gaithersburg, MD 20899–8552, United States
| | - Philip W. T. Pong
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong
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46
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Abstract
The manipulation of the molecular spin state by atom doping is an attractive strategy to confer desirable magnetic properties to molecules. Here, we present the formation of novel magnetic metallocenes by following this approach. In particular, two different on-surface procedures to build isolated and layer-integrated Co-ferrocene (CoFc) molecules on a metallic substrate via atomic manipulation and atom deposition are shown. The structure as well as the electronic properties of the so-formed molecule are investigated combining scanning tunneling microscopy and spectroscopy with density functional theory calculations. It is found that unlike single ferrocene a CoFc molecule possesses a magnetic moment as revealed by the Kondo effect. These results correspond to the first controlled procedure toward the development of tailored metallocene-based nanowires with a desired chemical composition, which are predicted to be promising materials for molecular spintronics.
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Affiliation(s)
- Maider Ormaza
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
| | - Roberto Robles
- ICN2 - Institut Català de Nanociéncia i Nanotecnologia , Campus UAB, 08193 Bellaterra (Barcelona), Spain
| | - Nicolas Bachellier
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
| | - Paula Abufager
- ICN2 - Institut Català de Nanociéncia i Nanotecnologia , Campus UAB, 08193 Bellaterra (Barcelona), Spain
- Instituto de Física de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Universidad Nacional de Rosario , Avenida Pellegrini 250 (2000) Rosario, Argentina
| | - Nicolás Lorente
- ICN2 - Institut Català de Nanociéncia i Nanotecnologia , Campus UAB, 08193 Bellaterra (Barcelona), Spain
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU) , Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - Laurent Limot
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
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47
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Abstract
We apply supramolecular assembly to control the adsorption configuration of Co-porphyrin molecules on Au(111) and Cu(111) surfaces. By means of cryogenic scanning tunneling microscopy, we reveal that the Kondo effect associated with the Co center is absent or present in different supramolecular systems. We perform first-principles calculations to obtain spin-polarized electronic structures and compute the Kondo temperatures using the Anderson impurity model. The switching behavior is traced to varied molecular adsorption heights in different supramolecular structures. These findings unravel that a competition between intermolecular interactions and molecule-substrate interactions subtly regulates the molecular Kondo effect in supramolecular systems.
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Affiliation(s)
- Qiushi Zhang
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
| | - Guowen Kuang
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
| | - Rui Pang
- Department of Physics, South University of Science and Technology of China , Shenzhen 518055, China
| | - Xingqiang Shi
- Department of Physics, South University of Science and Technology of China , Shenzhen 518055, China
| | - Nian Lin
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
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48
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Rakhmilevitch D, Tal O. Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching. Beilstein J Nanotechnol 2015; 6:2417-22. [PMID: 26734532 PMCID: PMC4685914 DOI: 10.3762/bjnano.6.249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 11/17/2015] [Indexed: 06/05/2023]
Abstract
The vibration-mediated Kondo effect attracted considerable theoretical interest during the last decade. However, due to lack of extensive experimental demonstrations, the fine details of the phenomenon were not addressed. Here, we analyze the evolution of vibration-mediated Kondo effect in molecular junctions during mechanical stretching. The described analysis reveals the different contributions of Kondo and inelastic transport.
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Affiliation(s)
- David Rakhmilevitch
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Oren Tal
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
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49
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Luo Y, Ronning F, Wakeham N, Lu X, Park T, Xu ZA, Thompson JD. Pressure-tuned quantum criticality in the antiferromagnetic Kondo semimetal CeNi2-δAs2. Proc Natl Acad Sci U S A 2015; 112:13520-4. [PMID: 26483465 DOI: 10.1073/pnas.1509581112] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The easily tuned balance among competing interactions in Kondo-lattice metals allows access to a zero-temperature, continuous transition between magnetically ordered and disordered phases, a quantum-critical point (QCP). Indeed, these highly correlated electron materials are prototypes for discovering and exploring quantum-critical states. Theoretical models proposed to account for the strange thermodynamic and electrical transport properties that emerge around the QCP of a Kondo lattice assume the presence of an indefinitely large number of itinerant charge carriers. Here, we report a systematic transport and thermodynamic investigation of the Kondo-lattice system CeNi2-δAs2 (δ ≈ 0.28) as its antiferromagnetic order is tuned by pressure and magnetic field to zero-temperature boundaries. These experiments show that the very small but finite carrier density of ~0.032 E-/formular unit in CeNi2-δAs2 leads to unexpected transport signatures of quantum criticality and the delayed development of a fully coherent Kondo-lattice state with decreasing temperature. The small carrier density and associated semimetallicity of this Kondo-lattice material favor an unconventional, local-moment type of quantum criticality and raises the specter of the Nozières exhaustion idea that an insufficient number of conduction-electron spins to separately screen local moments requires collective Kondo screening.
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50
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Frisenda R, Gaudenzi R, Franco C, Mas-Torrent M, Rovira C, Veciana J, Alcon I, Bromley ST, Burzurí E, van der Zant HSJ. Kondo effect in a neutral and stable all organic radical single molecule break junction. Nano Lett 2015; 15:3109-3114. [PMID: 25897770 DOI: 10.1021/acs.nanolett.5b00155] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Organic radicals are neutral, purely organic molecules exhibiting an intrinsic magnetic moment due to the presence of an unpaired electron in the molecule in its ground state. This property, added to the low spin-orbit coupling and weak hyperfine interactions, make neutral organic radicals good candidates for molecular spintronics insofar as the radical character is stable in solid state electronic devices. Here we show that the paramagnetism of the polychlorotriphenylmethyl radical molecule in the form of a Kondo anomaly is preserved in two- and three-terminal solid-state devices, regardless of mechanical and electrostatic changes. Indeed, our results demonstrate that the Kondo anomaly is robust under electrodes displacement and changes of the electrostatic environment, pointing to a localized orbital in the radical as the source of magnetism. Strong support to this picture is provided by density functional calculations and measurements of the corresponding nonradical species. These results pave the way toward the use of all-organic neutral radical molecules in spintronics devices and open the door to further investigations into Kondo physics.
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Affiliation(s)
- Riccardo Frisenda
- †Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - Rocco Gaudenzi
- †Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - Carlos Franco
- ‡Institut de Ciéncia de Materials de Barcelona (ICMAB-CSIC) and CIBER-BBN, Campus de la UAB, 08193, Bellaterra, Spain
| | - Marta Mas-Torrent
- ‡Institut de Ciéncia de Materials de Barcelona (ICMAB-CSIC) and CIBER-BBN, Campus de la UAB, 08193, Bellaterra, Spain
| | - Concepció Rovira
- ‡Institut de Ciéncia de Materials de Barcelona (ICMAB-CSIC) and CIBER-BBN, Campus de la UAB, 08193, Bellaterra, Spain
| | - Jaume Veciana
- ‡Institut de Ciéncia de Materials de Barcelona (ICMAB-CSIC) and CIBER-BBN, Campus de la UAB, 08193, Bellaterra, Spain
| | - Isaac Alcon
- §Departament de Química Física and Institut de Química Teórica i Computacional (IQTCUB), Universitat de Barcelona, E-08028 Barcelona, Spain
| | - Stefan T Bromley
- §Departament de Química Física and Institut de Química Teórica i Computacional (IQTCUB), Universitat de Barcelona, E-08028 Barcelona, Spain
- ∥Institició Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
| | - Enrique Burzurí
- †Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - Herre S J van der Zant
- †Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
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