1
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Yang YB, Wang JH, Li K, Xu Y. Higher-order topological phases in crystalline and non-crystalline systems: a review. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:283002. [PMID: 38574683 DOI: 10.1088/1361-648x/ad3abd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 04/04/2024] [Indexed: 04/06/2024]
Abstract
In recent years, higher-order topological phases have attracted great interest in various fields of physics. These phases have protected boundary states at lower-dimensional boundaries than the conventional first-order topological phases due to the higher-order bulk-boundary correspondence. In this review, we summarize current research progress on higher-order topological phases in both crystalline and non-crystalline systems. We firstly introduce prototypical models of higher-order topological phases in crystals and their topological characterizations. We then discuss effects of quenched disorder on higher-order topology and demonstrate disorder-induced higher-order topological insulators. We also review the theoretical studies on higher-order topological insulators in amorphous systems without any crystalline symmetry and higher-order topological phases in non-periodic lattices including quasicrystals, hyperbolic lattices, and fractals, which have no crystalline counterparts. We conclude the review by a summary of experimental realizations of higher-order topological phases and discussions on potential directions for future study.
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Affiliation(s)
- Yan-Bin Yang
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region of China, People's Republic of China
- Center for Quantum Information, IIIS, Tsinghua University, Beijing 100084, People's Republic of China
| | - Jiong-Hao Wang
- Center for Quantum Information, IIIS, Tsinghua University, Beijing 100084, People's Republic of China
| | - Kai Li
- Center for Quantum Information, IIIS, Tsinghua University, Beijing 100084, People's Republic of China
| | - Yong Xu
- Center for Quantum Information, IIIS, Tsinghua University, Beijing 100084, People's Republic of China
- Hefei National Laboratory, Hefei 230088, People's Republic of China
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2
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Le T, Zhang R, Li C, Jiang R, Sheng H, Tu L, Cao X, Lyu Z, Shen J, Liu G, Liu F, Wang Z, Lu L, Qu F. Magnetic field filtering of the boundary supercurrent in unconventional metal NiTe 2-based Josephson junctions. Nat Commun 2024; 15:2785. [PMID: 38555347 PMCID: PMC10981750 DOI: 10.1038/s41467-024-47103-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 03/15/2024] [Indexed: 04/02/2024] Open
Abstract
Topological materials with boundary (surface/edge/hinge) states have attracted tremendous research interest. Additionally, unconventional (obstructed atomic) materials have recently drawn lots of attention owing to their obstructed boundary states. Experimentally, Josephson junctions (JJs) constructed on materials with boundary states produce the peculiar boundary supercurrent, which was utilized as a powerful diagnostic approach. Here, we report the observations of boundary supercurrent in NiTe2-based JJs. Particularly, applying an in-plane magnetic field along the Josephson current can rapidly suppress the bulk supercurrent and retain the nearly pure boundary supercurrent, namely the magnetic field filtering of supercurrent. Further systematic comparative analysis and theoretical calculations demonstrate the existence of unconventional nature and obstructed hinge states in NiTe2, which could produce hinge supercurrent that accounts for the observation. Our results reveal the probable hinge states in unconventional metal NiTe2, and demonstrate in-plane magnetic field as an efficient method to filter out the bulk contributions and thereby to highlight the hinge states hidden in topological/unconventional materials.
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Affiliation(s)
- Tian Le
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Ruihan Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Changcun Li
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Ruiyang Jiang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Haohao Sheng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Linfeng Tu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- School of Physics, Nankai University, Tianjin, China
| | - Xuewei Cao
- School of Physics, Nankai University, Tianjin, China
| | - Zhaozheng Lyu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- Hefei National Laboratory, Hefei, China
| | - Jie Shen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, China
| | - Guangtong Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- Hefei National Laboratory, Hefei, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, China
| | - Fucai Liu
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China.
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou, China.
| | - Zhijun Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
| | - Li Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
- Hefei National Laboratory, Hefei, China.
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, China.
| | - Fanming Qu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
- Hefei National Laboratory, Hefei, China.
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, China.
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3
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Kim JK, Jeon KR, Sivakumar PK, Jeon J, Koerner C, Woltersdorf G, Parkin SSP. Intrinsic supercurrent non-reciprocity coupled to the crystal structure of a van der Waals Josephson barrier. Nat Commun 2024; 15:1120. [PMID: 38321041 PMCID: PMC10847146 DOI: 10.1038/s41467-024-45298-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 01/17/2024] [Indexed: 02/08/2024] Open
Abstract
Non-reciprocal electronic transport in a spatially homogeneous system arises from the simultaneous breaking of inversion and time-reversal symmetries. Superconducting and Josephson diodes, a key ingredient for future non-dissipative quantum devices, have recently been realized. Only a few examples of a vertical superconducting diode effect have been reported and its mechanism, especially whether intrinsic or extrinsic, remains elusive. Here we demonstrate a substantial supercurrent non-reciprocity in a van der Waals vertical Josephson junction formed with a Td-WTe2 barrier and NbSe2 electrodes that clearly reflects the intrinsic crystal structure of Td-WTe2. The Josephson diode efficiency increases with the Td-WTe2 thickness up to critical thickness, and all junctions, irrespective of the barrier thickness, reveal magneto-chiral characteristics with respect to a mirror plane of Td-WTe2. Our results, together with the twist-angle-tuned magneto-chirality of a Td-WTe2 double-barrier junction, show that two-dimensional materials promise vertical Josephson diodes with high efficiency and tunability.
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Affiliation(s)
- Jae-Keun Kim
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.
| | - Kun-Rok Jeon
- Department of Physics, Chung-Ang University (CAU), Seoul, 06974, Republic of Korea
| | - Pranava K Sivakumar
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Jaechun Jeon
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Chris Koerner
- Department of Physics, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 3, 06120, Halle, Germany
| | - Georg Woltersdorf
- Department of Physics, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 3, 06120, Halle, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany.
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4
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Chen P, Wang J, Wang G, Ye B, Zhou L, Wang L, Wang J, Zhang W, Chen W, Mei J, He H. Asymmetric edge supercurrents in MoTe 2 Josephson junctions. NANOSCALE ADVANCES 2024; 6:690-696. [PMID: 38235086 PMCID: PMC10791112 DOI: 10.1039/d3na00884c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 12/13/2023] [Indexed: 01/19/2024]
Abstract
To investigate the higher order topology in MoTe2, the supercurrent interference phenomena in Nb/MoTe2/Nb planar Josephson junctions have been systematically studied. By analyzing the obtained interference pattern of the critical supercurrents and performing a comparative study of the edge-touched and untouched junctions, it's found that the supercurrent is dominated by the edges, rather than the bulk or surfaces of MoTe2. An asymmetric Josephson effect with a field-tunable sign is also observed, indicating the nontrivial origin of the edge states. These results not only provide initial evidence for the hinge states in the higher order topological insulator MoTe2, but also demonstrate the potential applications of MoTe2-based Josephson junctions in rectifying the supercurrent.
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Affiliation(s)
- Pingbo Chen
- Department of Physics, Harbin Institute of Technology Harbin 150001 China
- Department of Physics, Southern University of Science and Technology Shenzhen 518055 China
| | - Jinhua Wang
- Department of Physics, Southern University of Science and Technology Shenzhen 518055 China
| | - Gongqi Wang
- Department of Physics, Southern University of Science and Technology Shenzhen 518055 China
| | - Bicong Ye
- Department of Physics, Southern University of Science and Technology Shenzhen 518055 China
- Department of Physics, The Hong Kong University of Science and Technology Clear Water Bay Hong Kong 999077 China
| | - Liang Zhou
- Department of Physics, Southern University of Science and Technology Shenzhen 518055 China
| | - Le Wang
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology Shenzhen 518055 China
| | - Jiannong Wang
- Department of Physics, The Hong Kong University of Science and Technology Clear Water Bay Hong Kong 999077 China
| | - Wenqing Zhang
- Department of Materials Science and Engineering, Southern University of Science and Technology Shenzhen 518055 China
- Shenzhen Key Laboratory for Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology Shenzhen 518055 China
| | - Weiqiang Chen
- Department of Physics, Southern University of Science and Technology Shenzhen 518055 China
- Shenzhen Key Laboratory for Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology Shenzhen 518055 China
| | - Jiawei Mei
- Department of Physics, Southern University of Science and Technology Shenzhen 518055 China
- Shenzhen Key Laboratory for Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology Shenzhen 518055 China
| | - Hongtao He
- Department of Physics, Southern University of Science and Technology Shenzhen 518055 China
- Shenzhen Key Laboratory for Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology Shenzhen 518055 China
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5
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Chu CG, Chen JJ, Wang AQ, Tan ZB, Li CZ, Li C, Brinkman A, Xiang PZ, Li N, Pan ZC, Lu HZ, Yu D, Liao ZM. Broad and colossal edge supercurrent in Dirac semimetal Cd 3As 2 Josephson junctions. Nat Commun 2023; 14:6162. [PMID: 37788988 PMCID: PMC10547728 DOI: 10.1038/s41467-023-41815-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 09/12/2023] [Indexed: 10/05/2023] Open
Abstract
Edge supercurrent has attracted great interest recently due to its crucial role in achieving and manipulating topological superconducting states. Proximity-induced superconductivity has been realized in quantum Hall and quantum spin Hall edge states, as well as in higher-order topological hinge states. Non-Hermitian skin effect, the aggregation of non-Bloch eigenstates at open boundaries, promises an abnormal edge channel. Here we report the observation of broad edge supercurrent in Dirac semimetal Cd3As2-based Josephson junctions. The as-grown Cd3As2 nanoplates are electron-doped by intrinsic defects, which enhance the non-Hermitian perturbations. The superconducting quantum interference indicates edge supercurrent with a width of ~1.6 μm and a magnitude of ~1 μA at 10 mK. The wide and large edge supercurrent is inaccessible for a conventional edge system and suggests the presence of non-Hermitian skin effect. A supercurrent nonlocality is also observed. The interplay between band topology and non-Hermiticity is beneficial for exploiting exotic topological matter.
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Affiliation(s)
- Chun-Guang Chu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | - Jing-Jing Chen
- Shenzhen Institute for Quantum Science and Engineering, Department of Physics, Southern University of Science and Technology, 518055, Shenzhen, China
- International Quantum Academy, 518048, Shenzhen, China
| | - An-Qi Wang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China.
| | - Zhen-Bing Tan
- Shenzhen Institute for Quantum Science and Engineering, Department of Physics, Southern University of Science and Technology, 518055, Shenzhen, China.
- International Quantum Academy, 518048, Shenzhen, China.
| | - Cai-Zhen Li
- Shenzhen Institute for Quantum Science and Engineering, Department of Physics, Southern University of Science and Technology, 518055, Shenzhen, China
- International Quantum Academy, 518048, Shenzhen, China
| | - Chuan Li
- MESA+ Institute for Nanotechnology, University of Twente, 7500 AE, Enschede, The Netherlands
| | - Alexander Brinkman
- MESA+ Institute for Nanotechnology, University of Twente, 7500 AE, Enschede, The Netherlands
| | - Peng-Zhan Xiang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | - Na Li
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | - Zhen-Cun Pan
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | - Hai-Zhou Lu
- Shenzhen Institute for Quantum Science and Engineering, Department of Physics, Southern University of Science and Technology, 518055, Shenzhen, China
| | - Dapeng Yu
- Shenzhen Institute for Quantum Science and Engineering, Department of Physics, Southern University of Science and Technology, 518055, Shenzhen, China
- International Quantum Academy, 518048, Shenzhen, China
- Hefei National Laboratory, 230088, Hefei, China
| | - Zhi-Min Liao
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China.
- Hefei National Laboratory, 230088, Hefei, China.
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6
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Endres M, Kononov A, Arachchige HS, Yan J, Mandrus D, Watanabe K, Taniguchi T, Schönenberger C. Current-Phase Relation of a WTe 2 Josephson Junction. NANO LETTERS 2023; 23:4654-4659. [PMID: 37155691 DOI: 10.1021/acs.nanolett.3c01416] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
When a topological insulator is incorporated into a Josephson junction, the system is predicted to reveal the fractional Josephson effect with a 4π-periodic current-phase relation. Here, we report the measurement of a 4π-periodic switching current through an asymmetric SQUID, formed by the higher-order topological insulator WTe2. Contrary to the established opinion, we show that a high asymmetry in critical current and negligible loop inductance are not sufficient by themselves to reliably measure the current-phase relation. Instead, we find that our measurement is heavily influenced by additional inductances originating from the self-formed PdTex inside the junction. We therefore develop a method to numerically recover the current-phase relation of the system and find the 1.5 μm long junction to be best described in the short ballistic limit. Our results highlight the complexity of subtle inductance effects that can give rise to misleading topological signatures in transport measurements.
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Affiliation(s)
- Martin Endres
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Artem Kononov
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Hasitha Suriya Arachchige
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jiaqiang Yan
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
- Material Science and Technology Division, Oak Ridge Laboratory, Oak Ridge, Tennessee 37831, United States
| | - David Mandrus
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
- Material Science and Technology Division, Oak Ridge Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Christian Schönenberger
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
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7
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Wang AQ, Xiang PZ, Zhao TY, Liao ZM. Topological nature of higher-order hinge states revealed by spin transport. Sci Bull (Beijing) 2022; 67:788-793. [DOI: 10.1016/j.scib.2022.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/16/2021] [Accepted: 02/07/2022] [Indexed: 12/01/2022]
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8
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Adhikari R, Adhikari S, Faina B, Terschanski M, Bork S, Leimhofer C, Cinchetti M, Bonanni A. Positive Magnetoresistance and Chiral Anomaly in Exfoliated Type-II Weyl Semimetal Td-WTe 2. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:2755. [PMID: 34685198 PMCID: PMC8541530 DOI: 10.3390/nano11102755] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/06/2021] [Accepted: 10/10/2021] [Indexed: 11/17/2022]
Abstract
Layered van der Waals semimetallic Td-WTe2, exhibiting intriguing properties which include non-saturating extreme positive magnetoresistance (MR) and tunable chiral anomaly, has emerged as a model topological type-II Weyl semimetal system. Here, ∼45 nm thick mechanically exfoliated flakes of Td-WTe2 are studied via atomic force microscopy, Raman spectroscopy, low-T/high-μ0H magnetotransport measurements and optical reflectivity. The contribution of anisotropy of the Fermi liquid state to the origin of the large positive transverse MR⊥ and the signature of chiral anomaly of the type-II Weyl Fermions are reported. The samples are found to be stable in air and no oxidation or degradation of the electronic properties is observed. A transverse MR⊥∼1200 % and an average carrier mobility of 5000 cm2V-1s-1 at T=5K for an applied perpendicular field μ0H⊥=7T are established. The system follows a Fermi liquid model for T≤50K and the anisotropy of the Fermi surface is concluded to be at the origin of the observed positive MR. Optical reflectivity measurements confirm the anisotropy of the electronic behaviour. The relative orientation of the crystal axes and of the applied electric and magnetic fields is proven to determine the observed chiral anomaly in the in-plane magnetotransport. The observed chiral anomaly in the WTe2 flakes is found to persist up to T=120K, a temperature at least four times higher than the ones reported to date.
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Affiliation(s)
- Rajdeep Adhikari
- Institut für Halbleiter-und-Festkörperphysik, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz, Austria; (S.A.); (B.F.)
| | - Soma Adhikari
- Institut für Halbleiter-und-Festkörperphysik, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz, Austria; (S.A.); (B.F.)
| | - Bogdan Faina
- Institut für Halbleiter-und-Festkörperphysik, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz, Austria; (S.A.); (B.F.)
| | - Marc Terschanski
- Department of Physics, TU Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany; (M.T.); (S.B.); (M.C.)
| | - Sophie Bork
- Department of Physics, TU Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany; (M.T.); (S.B.); (M.C.)
| | - Claudia Leimhofer
- Institut für Polymerwissenschaften, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz, Austria;
| | - Mirko Cinchetti
- Department of Physics, TU Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany; (M.T.); (S.B.); (M.C.)
| | - Alberta Bonanni
- Institut für Halbleiter-und-Festkörperphysik, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz, Austria; (S.A.); (B.F.)
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9
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Elfeky BH, Lotfizadeh N, Schiela WF, Strickland WM, Dartiailh M, Sardashti K, Hatefipour M, Yu P, Pankratova N, Lee H, Manucharyan VE, Shabani J. Local Control of Supercurrent Density in Epitaxial Planar Josephson Junctions. NANO LETTERS 2021; 21:8274-8280. [PMID: 34570504 DOI: 10.1021/acs.nanolett.1c02771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The critical current response to an applied out-of-plane magnetic field in a Josephson junction provides insight into the uniformity of its current distribution. In Josephson junctions with semiconducting weak links, the carrier density, and therefore the overall current distribution, can be modified electrostatically via metallic gates. Here, we show local control of the current distribution in an epitaxial Al-InAs Josephson junction equipped with five minigates. We demonstrate that not only can the junction width be electrostatically defined but also the current profile can be locally adjusted to form superconducting quantum interference devices. Our studies show enhanced edge conduction in such long junctions, which can be eliminated by minigates to create a uniform current distribution.
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Affiliation(s)
- Bassel Heiba Elfeky
- Department of Physics, New York University, New York, New York 10003, United States
| | - Neda Lotfizadeh
- Department of Physics, New York University, New York, New York 10003, United States
| | - William F Schiela
- Department of Physics, New York University, New York, New York 10003, United States
| | - William M Strickland
- Department of Physics, New York University, New York, New York 10003, United States
| | - Matthieu Dartiailh
- Department of Physics, New York University, New York, New York 10003, United States
| | - Kasra Sardashti
- Department of Physics, New York University, New York, New York 10003, United States
| | - Mehdi Hatefipour
- Department of Physics, New York University, New York, New York 10003, United States
| | - Peng Yu
- Department of Physics, New York University, New York, New York 10003, United States
| | - Natalia Pankratova
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, United States
| | - Hanho Lee
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, United States
| | - Vladimir E Manucharyan
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, United States
| | - Javad Shabani
- Department of Physics, New York University, New York, New York 10003, United States
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10
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Joseph NB, Narayan A. Topological properties of bulk and bilayer 2M WS 2: a first-principles study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:465001. [PMID: 34399421 DOI: 10.1088/1361-648x/ac1de1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Recently discovered 2M phase of bulk WS2was observed to exhibit superconductivity with a critical temperature of 8.8 K, the highest reported among superconducting transition metal dichalcogenides. Also predicted to support protected surface states, it could be a potential topological superconductor. In the present study, we perform a detailed first-principles analysis of bulk and bilayer 2M WS2. We report a comprehensive investigation of the bulk phase, comparing structural and electronic properties obtained from different exchange correlation functionals to the experimentally reported values. By calculation of theZ2invariant and surface states, we give support for its non-trivial band nature. Based on the insights gained from the analysis of the bulk phase, we predict bilayer 2M WS2as a new two-dimensional topological material. We demonstrate its dynamical stability from first-principles phonon computations and present its electronic properties, highlighting the band inversions between the Wdand Spstates. By means ofZ2invariant computations and a calculation of the edge states, we show that bilayer 2M WS2exhibits protected, robust edge states. The broken inversion symmetry in this newly proposed bilayer also leads to the presence of Berry curvature dipole and resulting non-linear responses. We compute the Berry curvature distribution and the dipole as a function of Fermi energy. We propose that Berry curvature dipole signals, which are absent in the centrosymmetric bulk 2M WS2, can be signatures of the bilayer. We hope our predictions lead to the experimental realization of this as-yet-undiscovered two-dimensional topological material.
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Affiliation(s)
- Nesta Benno Joseph
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Awadhesh Narayan
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
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11
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Choi YB, Xie Y, Chen CZ, Park J, Song SB, Yoon J, Kim BJ, Taniguchi T, Watanabe K, Kim J, Fong KC, Ali MN, Law KT, Lee GH. Evidence of higher-order topology in multilayer WTe 2 from Josephson coupling through anisotropic hinge states. NATURE MATERIALS 2020; 19:974-979. [PMID: 32632280 DOI: 10.1038/s41563-020-0721-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 06/01/2020] [Indexed: 06/11/2023]
Abstract
Td-WTe2 (non-centrosymmetric and orthorhombic), a type-II Weyl semimetal, is expected to have higher-order topological phases with topologically protected, helical one-dimensional hinge states when its Weyl points are annihilated. However, the detection of these hinge states is difficult due to the semimetallic behaviour of the bulk. In this study, we have spatially resolved the hinge states by analysing the magnetic field interference of the supercurrent in Nb-WTe2-Nb proximity Josephson junctions. The Josephson current along the a axis of the WTe2 crystal, but not along the b axis, showed a sharp enhancement at the edges of the junction, and the amount of enhanced Josephson current was comparable to the upper limits of a single one-dimensional helical channel. Our experimental observations suggest a higher-order topological phase in WTe2 and its corresponding anisotropic topological hinge states, in agreement with theoretical calculations. Our work paves the way for the study of hinge states in topological transition-metal dichalcogenides and analogous phases.
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Affiliation(s)
- Yong-Bin Choi
- Department of Physics, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Yingming Xie
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Chui-Zhen Chen
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- Institute for Advanced Study and School of Physical Science and Technology, Soochow University, Suzhou, China
| | - Jinho Park
- Department of Physics, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Su-Beom Song
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Jiho Yoon
- Max Plank Institute for Microstructure Physics, Halle (Saale), Germany
| | - B J Kim
- Department of Physics, Pohang University of Science and Technology, Pohang, Republic of Korea
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang, Republic of Korea
| | - Takashi Taniguchi
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Jonghwan Kim
- Department of Physics, Pohang University of Science and Technology, Pohang, Republic of Korea
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Kin Chung Fong
- Raytheon BBN Technologies, Quantum Information Processing Group, Cambridge, MA, USA.
| | - Mazhar N Ali
- Max Plank Institute for Microstructure Physics, Halle (Saale), Germany.
| | - Kam Tuen Law
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
| | - Gil-Ho Lee
- Department of Physics, Pohang University of Science and Technology, Pohang, Republic of Korea.
- Asia Pacific Center for Theoretical Physics, Pohang, Republic of Korea.
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