1
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Lee N, Pei C, Koo J, Qi Y, Kim SW. Pressure-Dependent Superconductivity in Topological Dirac Semimetal SrCuBi. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2400428. [PMID: 38747751 DOI: 10.1002/adma.202400428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 05/09/2024] [Indexed: 05/24/2024]
Abstract
The discovery of superconducting states in diverse topological materials generates a burgeoning interest to explore a topological superconductor and to realize a fault-tolerant topological quantum computation. A variety of routes to realize topological superconductors are proposed, and many types of topological materials are developed. However, a pristine topological material with a natural superconducting state is relatively rare as compared to topological materials with artificially induced superconductivity. Here, it is reported that the planar honeycomb structured 3D topological Dirac semimetal (TDS) SrCuBi, which is the Zintl phase, shows a natural surface superconductivity at 2.1 K under ambient pressure. It is clearly identified from theoretical calculations that a topologically nontrivial state exists on the (100) surface. Further, its superconducting transition temperature (Tc) increases by applying pressure, exhibiting a maximal Tc of 4.8 K under 6.2 GPa. It is believed that this discovery opens up a new possibility of exploring exotic Majorana fermions at the surface of 3D TDS superconductors.
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Affiliation(s)
- Nahyun Lee
- Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Cuiying Pei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, 201210, China
- Shanghai Key Laboratory of High-Resolution Electron Microscopy, ShanghaiTech University, Shanghai, 201210, China
| | - Jahyun Koo
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Yanpeng Qi
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, 201210, China
- Shanghai Key Laboratory of High-Resolution Electron Microscopy, ShanghaiTech University, Shanghai, 201210, China
| | - Sung Wng Kim
- Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea
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2
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Wang S, Zhong M, Liu H, Ju M. Coexistence of topological node surface and Dirac fermions in phonon-mediated superconductor YB 2C 2. Phys Chem Chem Phys 2024; 26:1454-1461. [PMID: 38113107 DOI: 10.1039/d3cp03678b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
The interaction between nontrivial topology and superconductivity in condensed matter physics has attracted tremendous research interest as it could give rise to exotic phenomena. Herein, based on first-principles calculations, we investigate the electronic structures, mechanical properties, topological properties, dynamic stability, electron-phonon coupling (EPC), and superconducting properties of the synthesized real material YB2C2. It is a tetragonal structure with P4/mbm symmetry and exhibits excellent stability. The calculated electronic band structures reveal that a zero-dimension (0D) Dirac point and two-dimensional (2D) nodal surface coexist near the Fermi level. A spin-orbit coupling (SOC) Dirac point with the topological Fermi arc is observed on the (001) surface. These nodal surfaces are protected by a two-fold screw axis and time-reversal symmetry. Based on the Bardeen-Cooper-Schrieffer theory, the superconducting transition temperature (Tc) in the range 1.25-4.45 K with different Coulomb repulsion constant μ* for YB2C2 is estimated to be consistent with previous experimental results. In addition, the EPC is mainly from the coupling between the dx2-y2 and dz2 orbitals of the Y atom and low-energy phonon modes. The presence of superconductivity and nontrivial topological surface state in YB2C2 suggests that it may be a candidate material for topological superconductors.
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Affiliation(s)
- Siqi Wang
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
| | - Mingmin Zhong
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
| | - Haibo Liu
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
| | - Meng Ju
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
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3
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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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4
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Duan W, Nie Z, Yan D, Su H, Chen Y, Chen Y, Shi Y, Song Y, Yuan H. Nodeless superconductivity in topologically nontrivial materials HfRuP and ZrRuAs. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:455601. [PMID: 36055225 DOI: 10.1088/1361-648x/ac8f0a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
Topologically nontrivial electronic states are recently found in a family of noncentrosymmetric transition metal pnictidesTRuX(T=Zr, Hf;X=P, As), presenting a unique platform for superconductivity to interplay with topological electronic states and asymmetric spin-orbit coupling. Here, we investigate the superconducting order parameter of HfRuP and ZrRuAs by measuring the magnetic penetration depth changeΔλ(T)using a method based on the tunnel-diode oscillator. Both compounds show clear exponential temperature dependence inΔλ(T)at low temperatures, suggesting fully-gapped superconductivity. Moreover, the superfluid densities in both HfRuP and ZrRuAs can be reasonably described by ans-wave superconducting model.
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Affiliation(s)
- Weiyin Duan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Zhiyong Nie
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Dayu Yan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Hang Su
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Yuxin Chen
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Ye Chen
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Youguo Shi
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yu Song
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Huiqiu Yuan
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310058, People's Republic of China
- State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310058, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
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5
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Li XG, Si JG, Shi LT, Liu PF, Zhang P, Wang BT. Superconductivity and topological states in hexagonal TaC and NbC. Phys Chem Chem Phys 2022; 24:18419-18426. [PMID: 35880864 DOI: 10.1039/d2cp02403a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Materials with superconductivity and a nontrivial band structure near the Fermi level are promising candidates in realizing topological superconductivity. Using first-principles calculations, we systematically investigated the stability, mechanical properties, superconductivity, electronic structures, and topological states of hexagonal TaC and NbC. The results show that they are stable and have excellent mechanical properties. We predicted that these two carbides are strong electron-phonon coupling superconductors with superconducting transition temperatures of 14.8 and 17.1 K, respectively. Strong coupling is mainly dominated by in-plane Ta/Nb atomic vibrations and in-plane Ta/Nb-dxy/dx2-y2 electronic orbitals. The electronic structure calculations demonstrate that a nodal line and a triply degenerate point coexist when not including the spin-orbit coupling (SOC) effect. After including the SOC effect, the nodal line is gapped. The complicated surface states are also calculated and need further experiments to verify. The present results indicate that the hexagonal TaC and NbC are potential candidates as topological superconductors, and pave the way towards exploring the superconductivity and topological materials in condensed matter systems.
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Affiliation(s)
- Xiang-Gui Li
- School of Applied Science, Beijing Information Science and Technology, Beijing, 100192, China
| | - Jian-Guo Si
- Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing, 100049, China. .,Spallation Neutron Source Science Center (SNSSC), Dongguan, 523803, China
| | - Lan-Ting Shi
- Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing, 100049, China. .,Spallation Neutron Source Science Center (SNSSC), Dongguan, 523803, China
| | - Peng-Fei Liu
- Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing, 100049, China. .,Spallation Neutron Source Science Center (SNSSC), Dongguan, 523803, China
| | - Ping Zhang
- School of Physics and Physical Engineering, Qufu Normal University, Qufu, 273165, China.,Institute of Applied Physics and Computational Mathematics, Beijing, 100088, China
| | - Bao-Tian Wang
- Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing, 100049, China. .,Spallation Neutron Source Science Center (SNSSC), Dongguan, 523803, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, 030006, China
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6
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Matsushita T, Ando J, Masaki Y, Mizushima T, Fujimoto S, Vekhter I. Spin-Nernst Effect in Time-Reversal-Invariant Topological Superconductors. PHYSICAL REVIEW LETTERS 2022; 128:097001. [PMID: 35302805 DOI: 10.1103/physrevlett.128.097001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/05/2022] [Indexed: 06/14/2023]
Abstract
We investigate the spin-Nernst effect in time-reversal-invariant topological superconductors, and show that it provides smoking-gun evidence for helical Cooper pairs. The spin-Nernst effect stems from asymmetric, in spin space, scattering of quasiparticles at nonmagnetic impurities, and generates a transverse spin current by the temperature gradient. Both the sign and the magnitude of the effect sensitively depend on the scattering phase shift at impurity sites. Therefore the spin-Nernst effect is uniquely suitable for identifying time-reversal-invariant topological superconducting orders.
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Affiliation(s)
- Taiki Matsushita
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Jiei Ando
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yusuke Masaki
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Takeshi Mizushima
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Satoshi Fujimoto
- Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
- Center for Quantum Information and Quantum Biology, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Ilya Vekhter
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803-4001, USA
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7
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Xu WX, Deng L, Wang Z, Chang J, Cheng C. A comparative study of the structural, electronic, vibrational, dielectric and elastic properties of the two phases CaAgBi through first-principles calculations. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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Ril’ AI, Marenkin SF. Cadmium Arsenides: Structure, Synthesis of Bulk and Film Crystals, Magnetic and Electrical Properties (Review). RUSS J INORG CHEM+ 2022. [DOI: 10.1134/s0036023621140059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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9
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Takane D, Kubota Y, Nakayama K, Kawakami T, Yamauchi K, Souma S, Kato T, Sugawara K, Ideta SI, Tanaka K, Kitamura M, Horiba K, Kumigashira H, Oguchi T, Takahashi T, Segawa K, Sato T. Dirac semimetal phase and switching of band inversion in XMg 2Bi 2 (X = Ba and Sr). Sci Rep 2021; 11:21937. [PMID: 34754019 PMCID: PMC8578568 DOI: 10.1038/s41598-021-01333-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/26/2021] [Indexed: 11/22/2022] Open
Abstract
Topological Dirac semimetals (TDSs) offer an excellent opportunity to realize outstanding physical properties distinct from those of topological insulators. Since TDSs verified so far have their own problems such as high reactivity in the atmosphere and difficulty in controlling topological phases via chemical substitution, it is highly desirable to find a new material platform of TDSs. By angle-resolved photoemission spectroscopy combined with first-principles band-structure calculations, we show that ternary compound BaMg2Bi2 is a TDS with a simple Dirac-band crossing around the Brillouin-zone center protected by the C3 symmetry of crystal. We also found that isostructural SrMg2Bi2 is an ordinary insulator characterized by the absence of band inversion due to the reduction of spin–orbit coupling. Thus, XMg2Bi2 (X = Sr, Ba, etc.) serves as a useful platform to study the interplay among crystal symmetry, spin–orbit coupling, and topological phase transition around the TDS phase.
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Affiliation(s)
- Daichi Takane
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Yuya Kubota
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Kosuke Nakayama
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan. .,Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Tokyo, 102-0076, Japan.
| | - Tappei Kawakami
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Kunihiko Yamauchi
- Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, 606-8501, Japan
| | - Seigo Souma
- Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan.,Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Takemi Kato
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Katsuaki Sugawara
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.,Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Tokyo, 102-0076, Japan.,Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan.,Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Shin-Ichiro Ideta
- UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki, 444-8585, Japan.,School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, 444-8585, Japan.,Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, 739-0046, Japan
| | - Kiyohisa Tanaka
- UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki, 444-8585, Japan.,School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, 444-8585, Japan
| | - Miho Kitamura
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, 305-0801, Japan
| | - Koji Horiba
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, 305-0801, Japan.,National Institutes for Quantum and Radiological Science and Technology (QST), Sayo, Hyogo, 679-5148, Japan
| | - Hiroshi Kumigashira
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai, 980-8577, Japan
| | - Tamio Oguchi
- Center for Spintronics Research Network, Osaka University, Toyonaka, 560-8531, Japan.,Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan
| | - Takashi Takahashi
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.,Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan.,Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Kouji Segawa
- Department of Physics, Kyoto Sangyo University, Kyoto, 603-8555, Japan
| | - Takafumi Sato
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan. .,Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan. .,Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan.
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10
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Emergence of topological superconductivity in doped topological Dirac semimetals under symmetry-lowering lattice distortions. Sci Rep 2021; 11:18539. [PMID: 34535739 PMCID: PMC8448755 DOI: 10.1038/s41598-021-97982-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 08/23/2021] [Indexed: 02/08/2023] Open
Abstract
Recently, unconventional superconductivity having a zero-bias conductance peak is reported in doped topological Dirac semimetal (DSM) with lattice distortion. Motivated by the experiments, we theoretically study the possible symmetry-lowering lattice distortions and their effects on the emergence of unconventional superconductivity in doped topological DSM. We find four types of symmetry-lowering lattice distortions that reproduce the crystal symmetries relevant to experiments from the group-theoretical analysis. Considering inter-orbital and intra-orbital electron density-density interactions, we calculate superconducting phase diagrams. We find that the lattice distortions can induce unconventional superconductivity hosting gapless surface Andreev bound states (SABS). Depending on the lattice distortions and superconducting pairing interactions, the unconventional inversion-odd-parity superconductivity can be either topological nodal superconductivity hosting a flat SABS or topological crystalline superconductivity hosting a gapless SABS. Remarkably, the lattice distortions increase the superconducting critical temperature, which is consistent with the experiments. Our work opens a pathway to explore and control pressure-induced topological superconductivity in doped topological semimetals.
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11
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Howlader S, Sheet G. Tip-induced superconductivity. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:403002. [PMID: 34087817 DOI: 10.1088/1361-648x/ac0850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 06/04/2021] [Indexed: 06/12/2023]
Abstract
It is widely believed that topological superconductivity, a hitherto elusive phase of quantum matter, can be achieved by inducing superconductivity in topological materials. In search of such topological superconductors, certain topological insulators (like, Bi2Se3) were successfully turned into superconductors by metal-ion (Cu, Pd, Sr, Nb etc) intercalation. Superconductivity could be induced in topological materials through applying pressure as well. For example, a pressure-induced superconducting phase was found in the topological insulator Bi2Se3. However, in all such cases, no conclusive signature of topological superconductivity was found. In this review, we will discuss about another novel way of inducing superconductivity in a non-superconducting topological material-by creating a mesoscopic interface on the material with a non-superconducting, normal metallic tip where the mesoscopic interface becomes superconducting. Such a phase is now known as a tip-induced superconducting (TISC) phase. This was first realized on Cd3As2in India. Following that, a large number of other topological materials were shown to display TISC. Since the TISC phase emerges only at a confined region under a mesoscopic point contact, traditional bulk tools for characterizing superconductivity cannot be employed to detect/confirm such a phase. On the other hand, such a point contact geometry is ideal for probing the possible existence of a temperature and magnetic field dependent superconducting energy gap and a temperature and magnetic field dependent critical current. We will review the details of the experimental signatures that can be used to prove the existence of superconductivity even when the 'text-book' tests for detecting superconductivity cannot be performed. Then, we will review various systems where a TISC phase could be realized.
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Affiliation(s)
- Sandeep Howlader
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, 81, Knowledge City, SAS Nagar, Manauli 140306, Punjab, India
| | - Goutam Sheet
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, 81, Knowledge City, SAS Nagar, Manauli 140306, Punjab, India
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12
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Abstract
Emergent electronic phenomena in iron-based superconductors have been at the forefront of condensed matter physics for more than a decade. Much has been learned about the origins and intertwined roles of ordered phases, including nematicity, magnetism, and superconductivity, in this fascinating class of materials. In recent years, focus has been centered on the peculiar and highly unusual properties of FeSe and its close cousins. This family of materials has attracted considerable attention due to the discovery of unexpected superconducting gap structures, a wide range of superconducting critical temperatures, and evidence for nontrivial band topology, including associated spin-helical surface states and vortex-induced Majorana bound states. Here, we review superconductivity in iron chalcogenide superconductors, including bulk FeSe, doped bulk FeSe, FeTe1−xSex, intercalated FeSe materials, and monolayer FeSe and FeTe1−xSex on SrTiO3. We focus on the superconducting properties, including a survey of the relevant experimental studies, and a discussion of the different proposed theoretical pairing scenarios. In the last part of the paper, we review the growing recent evidence for nontrivial topological effects in FeSe-related materials, focusing again on interesting implications for superconductivity.
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13
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Li Y, Xia J, Srivastava V. The Tetragonal Monoxide of Platinum: A New Platform for Investigating Nodal-Line and Nodal-Point Semimetallic Behavior. Front Chem 2020; 8:704. [PMID: 32923427 PMCID: PMC7457133 DOI: 10.3389/fchem.2020.00704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 07/08/2020] [Indexed: 11/15/2022] Open
Abstract
The search for new topological materials that are realistic to synthesize has attracted increasing attention. In this study, we systematically investigated the electronic, mechanical, and topological semimetallic properties, as well as the interesting surface states, of the tetragonal monoxide of platinum, which is realistic to synthesize, via a first-principles approach. Our calculated results indicate that PtO is a novel topological semimetal with double nodal lines in the k z = 0 plane and a pair of triple topological nodal points along the A'-M-A directions. Obvious surface states, including Fermi arc and drum-head-like surfaces, could be found around nodal points and nodal lines. The dynamic and mechanical stabilities of P4 2 /mmc-type PtO were examined in detail via calculation of the phonon dispersion and determination of elastic constants, respectively. Some other mechanical properties, including the bulk modulus, Young's modulus, shear modulus, Poisson's ratio, and Pugh's index, were considered in this study. P4 2 /mmc-type PtO provides a good research platform for investigation of novel behaviors that combine mechanical properties and rich topological elements.
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Affiliation(s)
- Yang Li
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming, China
- Department of Physics, Chongqing University of Arts and Sciences, Chongqing, China
| | - Jihong Xia
- Department of Physics, Chongqing University of Arts and Sciences, Chongqing, China
| | - Vipul Srivastava
- Department of Physics, School of Chemical Engineering and Physical Sciences, Lovely Professional University, Phagwara, India
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14
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Chen SZ, Li S, Chen Y, Duan W. Nodal Flexible-surface Semimetals: Case of Carbon Nanotube Networks. NANO LETTERS 2020; 20:5400-5407. [PMID: 32496795 DOI: 10.1021/acs.nanolett.0c01786] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Nodal surface-based topological semimetals (TSMs) are drawing attention due to their unique excitation and plasmon behaviors. However, only nodal flat-surface and nodal sphere TSMs are theoretically proposed due to strict symmetry requirements. Here, we propose that a series of surface-based topological phases can be realized in a tight-binding (TB) model with sublattice symmetry. These topological phases, named as nodal flexible-surface semimetals, include not only nodal surface and nodal sphere TSMs but also novel phases, like nodal tube, nodal crossbar, and nodal hourglass-like surface TSMs. According to the TB model, a family of carbon nanotube networks are then identified as nodal flexible-surface TSMs by first-principles calculations, and the topological phase transitions between these TSMs can be induced by strains. Moreover, the nodal flexible-surface TSMs with intrinsic high density of states at the Fermi level and special drumhead surface states are promising for studying high-temperature superconductors and strong correlation effects.
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Affiliation(s)
- Shi-Zhang Chen
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Siwen Li
- Faculty of Science, Jiangsu University, Zhenjiang 212013, Jiangsu, China
| | - Yuanping Chen
- Faculty of Science, Jiangsu University, Zhenjiang 212013, Jiangsu, China
| | - Wenhui Duan
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Tsinghua University, Beijing 100084, China
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
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15
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Yan Z, Wu Z, Huang W. Vortex End Majorana Zero Modes in Superconducting Dirac and Weyl Semimetals. PHYSICAL REVIEW LETTERS 2020; 124:257001. [PMID: 32639774 DOI: 10.1103/physrevlett.124.257001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 06/01/2020] [Accepted: 06/02/2020] [Indexed: 06/11/2023]
Abstract
Time-reversal invariant Dirac and Weyl semimetals in three dimensions (3D) can host open Fermi arcs and spin-momentum locking Fermi loops on the surfaces. We find that when they become superconducting with s-wave pairing and the doping is lower than a critical level, straight π-flux vortex lines terminating at surfaces with Fermi arcs or spin-momentum locking Fermi loops can realize 1D topological superconductivity and harbor Majorana zero modes at their ends. Remarkably, we find that the vortex-generation-associated Zeeman field can open (when the surfaces have only Fermi arcs) or enhance the topological gap protecting Majorana zero modes, which is contrary to the situation in superconducting topological insulators. By studying the tilting effect of bulk Dirac and Weyl cones, we further find that type-I Dirac and Weyl semimetals in general have a much broader topological regime than type-II ones. Our findings build up a connection between time-reversal invariant Dirac and Weyl semimetals and Majorana zero modes in vortices.
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Affiliation(s)
- Zhongbo Yan
- School of Physics, Sun Yat-Sen University, Guangzhou 510275, China
| | - Zhigang Wu
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Wen Huang
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
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16
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Zhang J, Huang GQ. The superconductivity and topological surface state of type-II Dirac semimetal NiTe 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:205702. [PMID: 31978915 DOI: 10.1088/1361-648x/ab6f84] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
NiTe2 is a type-II Dirac semimetal with the Dirac point very close to the Fermi level. In this paper, its electronic structure, phonon structure and electron-phonon interaction are studied via first-principles calculations. The noteworthy result is that the nontrival bands around the type-II Dirac point are strongly coupled with phonon modes, suggesting that they play an important role in superconductivity. Furthermore, the topological surface states on the (0 0 1) cleavage plane originated from the nontrivial Z 2 are well separated from the bulk states and can be tuned to approach the Fermi level by adding holes or by V substitution. The possible topological superconductivity in type-II Dirac semimetal NiTe2 is discussed.
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Affiliation(s)
- Jie Zhang
- Department of Physics, Nanjing Normal University, Nanjing 210023, People's Republic of China
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17
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Wang AQ, Ye XG, Yu DP, Liao ZM. Topological Semimetal Nanostructures: From Properties to Topotronics. ACS NANO 2020; 14:3755-3778. [PMID: 32286783 DOI: 10.1021/acsnano.9b07990] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Characterized by bulk Dirac or Weyl cones and surface Fermi-arc states, topological semimetals have sparked enormous research interest in recent years. The nanostructures, with large surface-to-volume ratio and easy field-effect gating, provide ideal platforms to detect and manipulate the topological quantum states. Exotic physical properties originating from these topological states endow topological semimetals attractive for future topological electronics (topotronics). For example, the linear energy dispersion relation is promising for broadband infrared photodetectors, the spin-momentum locking nature of topological surface states is valuable for spintronics, and the topological superconductivity is highly desirable for fault-tolerant qubits. For real-life applications, topological semimetals in the form of nanostructures are necessary in terms of convenient fabrication and integration. Here, we review the recent progresses in topological semimetal nanostructures and start with the quantum transport properties. Then topological semimetal-based electronic devices are introduced. Finally, we discuss several important aspects that should receive great effort in the future, including controllable synthesis, manipulation of quantum states, topological field effect transistors, spintronic applications, and topological quantum computation.
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Affiliation(s)
- An-Qi Wang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Xing-Guo Ye
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Da-Peng Yu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zhi-Min Liao
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China
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18
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Yin JX, Zhang SS, Dai G, Zhao Y, Kreisel A, Macam G, Wu X, Miao H, Huang ZQ, Martiny JHJ, Andersen BM, Shumiya N, Multer D, Litskevich M, Cheng Z, Yang X, Cochran TA, Chang G, Belopolski I, Xing L, Wang X, Gao Y, Chuang FC, Lin H, Wang Z, Jin C, Bang Y, Hasan MZ. Quantum Phase Transition of Correlated Iron-Based Superconductivity in LiFe_{1-x}Co_{x}As. PHYSICAL REVIEW LETTERS 2019; 123:217004. [PMID: 31809171 DOI: 10.1103/physrevlett.123.217004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Indexed: 06/10/2023]
Abstract
The interplay between unconventional Cooper pairing and quantum states associated with atomic scale defects is a frontier of research with many open questions. So far, only a few of the high-temperature superconductors allow this intricate physics to be studied in a widely tunable way. We use scanning tunneling microscopy to image the electronic impact of Co atoms on the ground state of the LiFe_{1-x}Co_{x}As system. We observe that impurities progressively suppress the global superconducting gap and introduce low energy states near the gap edge, with the superconductivity remaining in the strong-coupling limit. Unexpectedly, the fully opened gap evolves into a nodal state before the Cooper pair coherence is fully destroyed. Our systematic theoretical analysis shows that these new observations can be quantitatively understood by the nonmagnetic Born-limit scattering effect in an s±-wave superconductor, unveiling the driving force of the superconductor to metal quantum phase transition.
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Affiliation(s)
- Jia-Xin Yin
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Songtian S Zhang
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Guangyang Dai
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuanyuan Zhao
- School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Andreas Kreisel
- Institut für Theoretische Physik, Universität Leipzig, D-04103 Leipzig, Germany
| | - Gennevieve Macam
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
| | - Xianxin Wu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Institut für Theoretische Physik und Astrophysik, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
| | - Hu Miao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Zhi-Quan Huang
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
| | - Johannes H J Martiny
- Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Brian M Andersen
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Nana Shumiya
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Daniel Multer
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Maksim Litskevich
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Zijia Cheng
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Xian Yang
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Tyler A Cochran
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Guoqing Chang
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Lingyi Xing
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiancheng Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yi Gao
- Center for Quantum Transport and Thermal Energy Science, Jiangsu Key Lab on Opto-Electronic Technology, School of Physics and Technology, Nanjing Normal University, Nanjing 210097, China
| | - Feng-Chuan Chuang
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
| | - Hsin Lin
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Ziqiang Wang
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Changqing Jin
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yunkyu Bang
- Asia Pacific Center for Theoretical Physics and Department of Physics, POSTECH, Pohang, Gyeongbuk, 790-784, Korea
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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19
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Khoury JF, Rettie AJE, Khan MA, Ghimire NJ, Robredo I, Pfluger JE, Pal K, Wolverton C, Bergara A, Jiang JS, Schoop LM, Vergniory MG, Mitchell JF, Chung DY, Kanatzidis MG. A New Three-Dimensional Subsulfide Ir2In8S with Dirac Semimetal Behavior. J Am Chem Soc 2019; 141:19130-19137. [DOI: 10.1021/jacs.9b10147] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Jason F. Khoury
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Alexander J. E. Rettie
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Chemical Engineering, University College London, London WC1E 7JE, United Kingdom
| | - Mojammel A. Khan
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Nirmal J. Ghimire
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Physics and Astronomy, George Mason University, Fairfax, Virginia 22030, United States
| | - Iñigo Robredo
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastian, Spain
- Condensed Matter Physics Department, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain
| | - Jonathan E. Pfluger
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Koushik Pal
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Chris Wolverton
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Aitor Bergara
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastian, Spain
- Condensed Matter Physics Department, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain
- Centro de Física de Materiales, Centro Mixto CSIC-UPV/EHU, 20018 Donostia, Spain
| | - J. S. Jiang
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Leslie M. Schoop
- Department of Chemistry, Princeton University, Princeton, New Jersey 08540, United States
| | - Maia G. Vergniory
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastian, Spain
- Ikerbasque, Basque Foundation for Science, E-48011 Bilbao, Spain
| | - J. F. Mitchell
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Duck Young Chung
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Mercouri G. Kanatzidis
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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20
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Kobayashi S, Yamakage A, Tanaka Y, Sato M. Majorana Multipole Response of Topological Superconductors. PHYSICAL REVIEW LETTERS 2019; 123:097002. [PMID: 31524460 DOI: 10.1103/physrevlett.123.097002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Indexed: 06/10/2023]
Abstract
In contrast to elementary Majorana particles, emergent Majorana fermions (MFs) in condensed-matter systems may have electromagnetic multipoles. We developed a general theory of magnetic multipoles for helical MFs on time-reversal-invariant superconductors. The results show that the multipole response is governed by crystal symmetry, and that a one-to-one correspondence exists between the symmetry of Cooper pairs and the representation of magnetic multipoles under crystal symmetry. The latter property provides a way to identify unconventional pairing symmetry via the magnetic response of helical MFs. We also find that most helical MFs exhibit a magnetic-dipole response, but those on superconductors with spin-3/2 electrons may display a magnetic-octupole response in leading order, which uniquely characterizes high-spin superconductors. Detection of such an octupole response provides direct evidence of high-spin superconductivity, such as in half-Heusler superconductors.
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Affiliation(s)
- Shingo Kobayashi
- Institute for Advanced Research, Nagoya University, Nagoya 464-8601, Japan
- Department of Applied Physics, Nagoya University, Nagoya 464-8603, Japan
| | - Ai Yamakage
- Department of Physics, Nagoya University, Nagoya 464-8602, Japan
| | - Yukio Tanaka
- Department of Applied Physics, Nagoya University, Nagoya 464-8603, Japan
| | - Masatoshi Sato
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan
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21
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Qin S, Hu L, Le C, Zeng J, Zhang FC, Fang C, Hu J. Quasi-1D Topological Nodal Vortex Line Phase in Doped Superconducting 3D Dirac Semimetals. PHYSICAL REVIEW LETTERS 2019; 123:027003. [PMID: 31386504 DOI: 10.1103/physrevlett.123.027003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/10/2019] [Indexed: 06/10/2023]
Abstract
We study vortex bound states in three-dimensional (3D) superconducting Dirac semimetals with time reversal symmetry. We find that there exist robust gapless vortex bound states propagating along the vortex line in the s-wave superconducting state. We refer to this newly found phase as the quasi-1D nodal vortex line phase. According to the Altland-Zirnbauer classification, the phase is characterized by a topological index (ν;N) at k_{z}=0 and k_{z}=π, where ν is the Z_{2} topological invariant for a 0D class-D system and N is the Z topological invariant for a 0D class-A system. Furthermore, we show that the vortex end Majorana zero mode can coexist with the quasi-1D nodal phase in certain types of Dirac semimetals. The possible experimental observations and material realization of such nodal vortex line states are discussed.
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Affiliation(s)
- Shengshan Qin
- Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing National Research Center for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Lunhui Hu
- Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Department of Physics, University of California, San Diego, California 92093, USA
| | - Congcong Le
- Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing National Research Center for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jinfeng Zeng
- Beijing National Research Center for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Science, Beijing 100049, China
| | - Fu-Chun Zhang
- Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Chen Fang
- Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing National Research Center for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jiangping Hu
- Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing National Research Center for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- South Bay Interdisciplinary Science Center, Dongguan, Guangdong Province, China
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22
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Daido A, Yoshida T, Yanase Y. Z_{4} Topological Superconductivity in UCoGe. PHYSICAL REVIEW LETTERS 2019; 122:227001. [PMID: 31283273 DOI: 10.1103/physrevlett.122.227001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Indexed: 06/09/2023]
Abstract
Topological nonsymmorphic crystalline superconductivity (TNCS) is an intriguing phase of matter, offering a platform to study the interplay between topology, superconductivity, and nonsymmorphic crystalline symmetries. Interestingly, some of TNCSs are classified into Z_{4} topological phases, which have unique surface states referred to as a Möbius strip or an hourglass, and they have not been achieved in symmorphic superconductors. However, material realization of Z_{4} TNCS has never been known, to the best of our knowledge. Here, we propose that the paramagnetic superconducting phase of UCoGe under pressure is a promising candidate of Z_{4}-nontrivial TNCS enriched by glide symmetry. We evaluate Z_{4} invariants of UCoGe by deriving the formulas relating Z_{4} invariants to the topology of Fermi surfaces. Applying the formulas and previous ab initio calculations, we clarify that three odd-parity representations out of four are Z_{4}-nontrivial TNCS, whereas the other is also Z_{2}-nontrivial TNCS. We also discuss possible Z_{4} TNCS in CrAs and related materials.
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Affiliation(s)
- Akito Daido
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Tsuneya Yoshida
- Department of Physics, University of Tsukuba, Ibaraki 305-8571, Japan
| | - Youichi Yanase
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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23
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Sukhachov PO, Gorbar EV, Shovkovy IA, Miransky VA. Inter-node superconductivity in strained Weyl semimetals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:055602. [PMID: 30523810 DOI: 10.1088/1361-648x/aaf12a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The effects of a strain-induced pseudomagnetic field on inter-node spin-triplet superconducting states in Weyl semimetals are studied by using the quasiclassical Eilenberger formalism. It is found that the Cooper pairing with spins parallel to the pseudomagnetic field has the lowest energy among the spin-triplet states and its gap does not depend on the strength of the field. In such a state, both electric and chiral superconducting currents are absent. This is in contrast to the superconducting states with the spins of Cooper pairs normal to the field, which support a nonzero chiral current and are inhibited by the strain-induced pseudomagnetic field. The corresponding critical value of the field, which separates the normal and superconducting phases, is estimated.
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Affiliation(s)
- P O Sukhachov
- Department of Applied Mathematics, Western University, London, Ontario, N6A 5B7, Canada
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24
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Lin BC, Wang S, Wiedmann S, Lu JM, Zheng WZ, Yu D, Liao ZM. Observation of an Odd-Integer Quantum Hall Effect from Topological Surface States in Cd_{3}As_{2}. PHYSICAL REVIEW LETTERS 2019; 122:036602. [PMID: 30735405 DOI: 10.1103/physrevlett.122.036602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Indexed: 06/09/2023]
Abstract
The quantum Hall effect (QHE) in a 3D Dirac semimetal thin film is attributed to either the quantum confinement induced bulk subbands or the Weyl orbits that connect the opposite surfaces via bulk Weyl nodes. However, it is still unknown whether the QHE based on the Weyl orbit can survive as the bulk Weyl nodes are gapped. Moreover, there are closed Fermi loops rather than open Fermi arcs on the Dirac semimetal surface, which can also host the QHE. Here we report the QHE in the 3D Dirac semimetal Cd_{3}As_{2} nanoplate by tuning the gate voltage under a fixed 30 T magnetic field. The quantized Hall plateaus at odd filling factors are observed as a magnetic field along the [001] crystal direction, indicating a Berry's phase π from the topological surface states. Furthermore, even filling factors are observed when the magnetic field is along the [112] direction, indicating the C_{4} rotational symmetry breaking and a topological phase transition. The results shed light on the understanding of QHE in 3D Cd_{3}As_{2}.
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Affiliation(s)
- Ben-Chuan Lin
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Shuo Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Steffen Wiedmann
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, Nijmegen 6525 ED, Netherlands
- Radboud University, Institute for Molecules and Materials, Nijmegen 6525 AJ, Netherlands
| | - Jian-Ming Lu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, Nijmegen 6525 ED, Netherlands
| | - Wen-Zhuang Zheng
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Dapeng Yu
- Institute for Quantum Science and Engineering and Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China
| | - Zhi-Min Liao
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Beijing Key Laboratory of Quantum Devices, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
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25
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Wang AQ, Li CZ, Li C, Liao ZM, Brinkman A, Yu DP. 4π-Periodic Supercurrent from Surface States in Cd_{3}As_{2} Nanowire-Based Josephson Junctions. PHYSICAL REVIEW LETTERS 2018; 121:237701. [PMID: 30576175 DOI: 10.1103/physrevlett.121.237701] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Indexed: 06/09/2023]
Abstract
The combination of superconductivity and surface states in Dirac semimetal can produce a 4π-periodic supercurrent in a Josephson junction configuration, which can be revealed by the missing of odd Shapiro steps (especially the n=1 step). However, the suppression of the n=1 step is also anticipated in the high-power oscillatory regime of the ordinary 2π-periodic Josephson effect, which is irrelevant to the 4π-periodic supercurrent. Here, in order to identify the origin of the suppressed n=1 step, we perform the measurements of radio frequency irradiation on Nb-Dirac semimetal Cd_{3}As_{2} nanowire-Nb junctions with continuous power dependence at various frequencies. Besides the n=1 step suppression, we uncover a residual supercurrent of first node at the n=0 step, which provides a direct and predominant signature of the 4π-periodic supercurrent. Furthermore, by tuning the gate voltage, we can modulate the surface and bulk state contribution and the visibility of the n=1 step. Our results provide deep insights to explore the topological superconductivity in Dirac semimetals.
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Affiliation(s)
- An-Qi Wang
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Cai-Zhen Li
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Chuan Li
- MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands
| | - Zhi-Min Liao
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Beijing Key Laboratory of Quantum Devices, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Alexander Brinkman
- MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands
| | - Da-Peng Yu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
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26
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Wang H, Ma L, Wang J. Tip-induced or enhanced superconductivity: a way to detect topological superconductivity. Sci Bull (Beijing) 2018; 63:1141-1158. [PMID: 36658994 DOI: 10.1016/j.scib.2018.07.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 01/21/2023]
Abstract
Topological materials, hosting topological nontrivial electronic band, have attracted widespread attentions. As an application of topology in physics, the discovery and study of topological materials not only enrich the existing theoretical framework of physics, but also provide fertile ground for investigations on low energy excitations, such as Weyl fermions and Majorana fermions, which have not been observed yet as fundamental particles. These quasiparticles with exotic physical properties make topological materials the cutting edge of scientific research and a new favorite of high tech. As a typical example, Majorana fermions, predicted to exist in the edge state of topological superconductors, are proposed to implement topological error-tolerant quantum computers. Thus, the detection of topological superconductivity has become a frontier in condensed matter physics and materials science. Here, we review a way to detect topological superconductivity triggered by the hard point contact: tip-induced superconductivity (TISC) and tip-enhanced superconductivity (TESC). The TISC refers to the superconductivity induced by a non-superconducting tip at the point contact on non-superconducting materials. We take the elaboration of the chief experimental achievement of TISC in topological Dirac semimetal Cd3As2 and Weyl semimetal TaAs as key components of this article for detecting topological superconductivity. Moreover, we also briefly introduce the main results of another exotic effect, TESC, in superconducting Au2Pb and Sr2RuO4 single crystals, which are respectively proposed as the candidates of helical topological superconductor and chiral topological superconductor. Related results and the potential mechanism are conducive to improving the comprehension of how to induce and enhance the topological superconductivity.
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Affiliation(s)
- He Wang
- Tianjin International Center for Nano Particles and Nano Systems, Tianjin University, Tianjin 300072, China; International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Lei Ma
- Tianjin International Center for Nano Particles and Nano Systems, Tianjin University, Tianjin 300072, China.
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China; State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
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27
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Fei F, Bo X, Wang P, Ying J, Li J, Chen K, Dai Q, Chen B, Sun Z, Zhang M, Qu F, Zhang Y, Wang Q, Wang X, Cao L, Bu H, Song F, Wan X, Wang B. Band Structure Perfection and Superconductivity in Type-II Dirac Semimetal Ir 1-x Pt x Te 2. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1801556. [PMID: 30019415 DOI: 10.1002/adma.201801556] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 06/13/2018] [Indexed: 06/08/2023]
Abstract
The discovery of a new type-II Dirac semimetal in Ir1-x Ptx Te2 with optimized band structure is described. Pt dopants protect the crystal structure holding the Dirac cones and tune the Fermi level close to the Dirac point. The type-II Dirac dispersion in Ir1-x Ptx Te2 is confirmed by angle-resolved photoemission spectroscopy and first-principles calculations. Superconductivity is also observed and persists when the Fermi level aligns with the Dirac points. Ir1-x Ptx Te2 is an ideal platform for further studies on the exotic properties and potential applications of type-II DSMs, and opens up a new route for the investigation of the possible topological superconductivity and Majorana physics.
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Affiliation(s)
- Fucong Fei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Xiangyan Bo
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Pengdong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, China
| | - Jianghua Ying
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jian Li
- Westlake Institute for Advanced Study, Hangzhou, 310012, China
| | - Ke Chen
- Nanophotonics Research Division, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Qing Dai
- Nanophotonics Research Division, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Bo Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Zhe Sun
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, China
| | - Minhao Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Fanming Qu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yi Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Qianghua Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Xuefeng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China
| | - Lu Cao
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Haijun Bu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Xiangang Wan
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
| | - Baigeng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Department of Physics, Nanjing University, Nanjing, 210093, China
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28
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Huang C, Narayan A, Zhang E, Liu Y, Yan X, Wang J, Zhang C, Wang W, Zhou T, Yi C, Liu S, Ling J, Zhang H, Liu R, Sankar R, Chou F, Wang Y, Shi Y, Law KT, Sanvito S, Zhou P, Han Z, Xiu F. Inducing Strong Superconductivity in WTe 2 by a Proximity Effect. ACS NANO 2018; 12:7185-7196. [PMID: 29901987 DOI: 10.1021/acsnano.8b03102] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The search for proximity-induced superconductivity in topological materials has generated widespread interest in the condensed matter physics community. The superconducting states inheriting nontrivial topology at interfaces are expected to exhibit exotic phenomena such as topological superconductivity and Majorana zero modes, which hold promise for applications in quantum computation. However, a practical realization of such hybrid structures based on topological semimetals and superconductors has hitherto been limited. Here, we report the strong proximity-induced superconductivity in type-II Weyl semimetal WTe2, in a van der Waals hybrid structure obtained by mechanically transferring NbSe2 onto various thicknesses of WTe2. When the WTe2 thickness ( tWTe2) reaches 21 nm, the superconducting transition occurs around the critical temperature ( Tc) of NbSe2 with a gap amplitude (Δp) of 0.38 meV and an unexpected ultralong proximity length ( lp) up to 7 μm. With the thicker 42 nm WTe2 layer, however, the proximity effect yields Tc ≈ 1.2 K, Δp = 0.07 meV, and a short lp of less than 1 μm. Our theoretical calculations, based on the Bogoliubov-de Gennes equations in the clean limit, predict that the induced superconducting gap is a sizable fraction of the NbSe2 superconducting one when tWTe2 is less than 30 nm and then decreases quickly as tWTe2 increases. This agrees qualitatively well with the experiments. Such observations form a basis in the search for superconducting phases in topological semimetals.
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Affiliation(s)
- Ce Huang
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Awadhesh Narayan
- Materials Theory , ETH Zurich , Wolfgang-Pauli-Strasse 27 , CH 8093 Zurich , Switzerland
| | - Enze Zhang
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Yanwen Liu
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Xiao Yan
- State Key Laboratory of ASIC and System, Department of Microelectronics , Fudan University , Shanghai 200433 , China
| | - Jiaxiang Wang
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Cheng Zhang
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Weiyi Wang
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Tong Zhou
- Department of Physics , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong, China
| | - Changjiang Yi
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics , Chinese Academy of Sciences , Beijing 100190 , China
| | - Shanshan Liu
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Jiwei Ling
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Huiqin Zhang
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Ran Liu
- State Key Laboratory of Surface Physics and Department of Physics , Fudan University , Shanghai 200433 , China
- Institute for Nanoelectronic Devices and Quantum Computing , Fudan University , Shanghai 200433 , China
| | - Raman Sankar
- Institute of Physics , Academia Sinica , Taipei 11529 , Taiwan, China
- Center for Condensed Matter Sciences , National Taiwan University , Taipei 10617 , Taiwan, China
| | - Fangcheng Chou
- Center for Condensed Matter Sciences , National Taiwan University , Taipei 10617 , Taiwan, China
- National Synchrotron Radiation Research Center , Hsinchu 30076 , Taiwan, China
- Taiwan Consortium of Emergent Crystalline Materials , Ministry of Science and Technology , Taipei 10622 , Taiwan, China
| | - Yihua Wang
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Youguo Shi
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics , Chinese Academy of Sciences , Beijing 100190 , China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Kam Tuen Law
- Department of Physics , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong, China
| | - Stefano Sanvito
- School of Physics, AMBER and CRANN Institute , Trinity College , Dublin 2 , Ireland
| | - Peng Zhou
- State Key Laboratory of ASIC and System, Department of Microelectronics , Fudan University , Shanghai 200433 , China
| | - Zheng Han
- Shenyang National Laboratory for Materials Science, Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110016 , China
| | - Faxian Xiu
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
- Collaborative Innovation Center of Advanced Microstructures , Nanjing 210093 , China
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29
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Abstract
Two-dimensional single-layer boron (borophene) has emerged as a new material with several intriguing properties. Recently, the β12 polymorph of borophene was grown on Ag(111), and observed to host Dirac fermions. Similar to graphene, β12 borophene can be described as atom-vacancy pseudoalloy on a closed-packed triangular lattice; however, unlike graphene, the origin of its Dirac fermions is yet unclear. Here, using first-principles calculations, we probe the origin of Dirac fermions in freestanding and Ag(111)-supported β12 borophene. The freestanding β12 sheet hosts two Dirac cones and a topologically nontrivial Dirac nodal line with interesting Dirac-like edge states. On Ag(111), the Dirac cones develop a gap, whereas the topologically protected nodal line remains intact, and its position in the Brillouin zone matches that of the Dirac-like electronic states seen in the experiment. The presence of nontrivial topological states near the Fermi level in borophene makes its electronic properties important for both fundamental and applied research.
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Affiliation(s)
- Sunny Gupta
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
| | - Alex Kutana
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
| | - Boris I Yakobson
- Department of Materials Science and Nanoengineering , Rice University , Houston , Texas 77005 , United States
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30
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Sato M, Ando Y. Topological superconductors: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:076501. [PMID: 28367833 DOI: 10.1088/1361-6633/aa6ac7] [Citation(s) in RCA: 258] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
This review elaborates pedagogically on the fundamental concept, basic theory, expected properties, and materials realizations of topological superconductors. The relation between topological superconductivity and Majorana fermions are explained, and the difference between dispersive Majorana fermions and a localized Majorana zero mode is emphasized. A variety of routes to topological superconductivity are explained with an emphasis on the roles of spin-orbit coupling. Present experimental situations and possible signatures of topological superconductivity are summarized with an emphasis on intrinsic topological superconductors.
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Affiliation(s)
- Masatoshi Sato
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan
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31
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O'Brien TE, Beenakker CWJ, Adagideli I. Superconductivity Provides Access to the Chiral Magnetic Effect of an Unpaired Weyl Cone. PHYSICAL REVIEW LETTERS 2017; 118:207701. [PMID: 28581792 DOI: 10.1103/physrevlett.118.207701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Indexed: 06/07/2023]
Abstract
The massless fermions of a Weyl semimetal come in two species of opposite chirality, in two cones of the band structure. As a consequence, the current j induced in one Weyl cone by a magnetic field B [the chiral magnetic effect (CME)] is canceled in equilibrium by an opposite current in the other cone. Here, we show that superconductivity offers a way to avoid this cancellation, by means of a flux bias that gaps out a Weyl cone jointly with its particle-hole conjugate. The remaining gapless Weyl cone and its particle-hole conjugate represent a single fermionic species, with renormalized charge e^{*} and a single chirality ± set by the sign of the flux bias. As a consequence, the CME is no longer canceled in equilibrium but appears as a supercurrent response ∂j/∂B=±(e^{*}e/h^{2})μ along the magnetic field at chemical potential μ.
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Affiliation(s)
- T E O'Brien
- Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands
| | - C W J Beenakker
- Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands
| | - I Adagideli
- Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands
- Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, Istanbul 34956, Turkey
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32
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Wang H, Wang H, Chen Y, Luo J, Yuan Z, Liu J, Wang Y, Jia S, Liu XJ, Wei J, Wang J. Discovery of tip induced unconventional superconductivity on Weyl semimetal. Sci Bull (Beijing) 2017; 62:425-430. [PMID: 36659286 DOI: 10.1016/j.scib.2017.02.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 02/21/2017] [Accepted: 02/21/2017] [Indexed: 01/21/2023]
Abstract
Weyl fermion is a massless Dirac fermion with definite chirality, which has been long pursued since 1929. Though it has not been observed as a fundamental particle in nature, Weyl fermion can be realized as low-energy excitation around Weyl point in Weyl semimetal, which possesses Weyl fermion cones in the bulk and nontrivial Fermi arc states on the surface. As a firstly discovered Weyl semimetal, TaAs crystal possesses 12 pairs of Weyl points in the momentum space, which are topologically protected against small perturbations. Here, we report for the first time the tip induced superconductivity on TaAs crystal by point contact spectroscopy. The zero bias conductance peak as well as a conductance plateau with double conductance peaks and sharp double dips are observed in the point contact spectra simultaneously, indicating unconventional superconductivity. Our further theoretical study suggests that the induced superconductivity may have nontrivial topology. The present work opens a new route in investigating the novel superconducting states based on Weyl materials.
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Affiliation(s)
- He Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Huichao Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Yuqin Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Jiawei Luo
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Zhujun Yuan
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Jun Liu
- Center of Electron Microscopy, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Yong Wang
- Center of Electron Microscopy, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Xiong-Jun Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China.
| | - Jian Wei
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China.
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China.
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33
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Oudah M, Ikeda A, Hausmann JN, Yonezawa S, Fukumoto T, Kobayashi S, Sato M, Maeno Y. Superconductivity in the antiperovskite Dirac-metal oxide Sr 3-xSnO. Nat Commun 2016; 7:13617. [PMID: 27941805 PMCID: PMC5159807 DOI: 10.1038/ncomms13617] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Accepted: 10/18/2016] [Indexed: 11/09/2022] Open
Abstract
Investigations of perovskite oxides triggered by the discovery of high-temperature and unconventional superconductors have had crucial roles in stimulating and guiding the development of modern condensed-matter physics. Antiperovskite oxides are charge-inverted counterpart materials to perovskite oxides, with unusual negative ionic states of a constituent metal. No superconductivity was reported among the antiperovskite oxides so far. Here we present the first superconducting antiperovskite oxide Sr3-xSnO with the transition temperature of around 5 K. Sr3SnO possesses Dirac points in its electronic structure, and we propose from theoretical analysis a possibility of a topological odd-parity superconductivity analogous to the superfluid 3He-B in moderately hole-doped Sr3-xSnO. We envision that this discovery of a new class of oxide superconductors will lead to a rapid progress in physics and chemistry of antiperovskite oxides consisting of unusual metallic anions.
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Affiliation(s)
- Mohamed Oudah
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Atsutoshi Ikeda
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Jan Niklas Hausmann
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.,Department of Chemistry, Faculty of Mathematics and Natural Sciences, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, Berlin 12489, Germany
| | - Shingo Yonezawa
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Toshiyuki Fukumoto
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Shingo Kobayashi
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan.,Institute for Advanced Research, Nagoya University, Nagoya 464-8601, Japan
| | - Masatoshi Sato
- Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Yoshiteru Maeno
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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34
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Kozii V, Venderbos JWF, Fu L. Three-dimensional Majorana fermions in chiral superconductors. SCIENCE ADVANCES 2016; 2:e1601835. [PMID: 27957543 PMCID: PMC5142806 DOI: 10.1126/sciadv.1601835] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 11/03/2016] [Indexed: 05/31/2023]
Abstract
Using a systematic symmetry and topology analysis, we establish that three-dimensional chiral superconductors with strong spin-orbit coupling and odd-parity pairing generically host low-energy nodal quasiparticles that are spin-nondegenerate and realize Majorana fermions in three dimensions. By examining all types of chiral Cooper pairs with total angular momentum J formed by Bloch electrons with angular momentum j in crystals, we obtain a comprehensive classification of gapless Majorana quasiparticles in terms of energy-momentum relation and location on the Fermi surface. We show that the existence of bulk Majorana fermions in the vicinity of spin-selective point nodes is rooted in the nonunitary nature of chiral pairing in spin-orbit-coupled superconductors. We address experimental signatures of Majorana fermions and find that the nuclear magnetic resonance spin relaxation rate is significantly suppressed for nuclear spins polarized along the nodal direction as a consequence of the spin-selective Majorana nature of nodal quasiparticles. Furthermore, Majorana nodes in the bulk have nontrivial topology and imply the presence of Majorana bound states on the surface, which form arcs in momentum space. We conclude by proposing the heavy fermion superconductor PrOs4Sb12 and related materials as promising candidates for nonunitary chiral superconductors hosting three-dimensional Majorana fermions.
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Affiliation(s)
- Vladyslav Kozii
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jörn W. F. Venderbos
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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35
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Ma F, Jiao Y, Gao G, Gu Y, Bilic A, Sanvito S, Du A. Substantial Band-Gap Tuning and a Strain-Controlled Semiconductor to Gapless/Band-Inverted Semimetal Transition in Rutile Lead/Stannic Dioxide. ACS APPLIED MATERIALS & INTERFACES 2016; 8:25667-25673. [PMID: 27658731 DOI: 10.1021/acsami.6b09967] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
By first-principle calculations, we have systematically studied the effect of strain/pressure on the electronic structure of rutile lead/stannic dioxide (PbO2/SnO2). We find that pressure/strain has a significant impact on the electronic structure of PbO2/SnO2. Not only can the band gap be substantially tuned by pressure/strain, but also a transition between a semiconductor and a gapless/band-inverted semimetal can be manipulated. Furthermore, the semimetallic state is robust under strain, indicating a bright perspective for electronics applications. In addition, a practical approach to realizing strain in SnO2 is then proposed by substituting tin (Sn) with lead (Pb), which also can trigger the transition from a large-band-gap to a moderate-gap semiconductor with enhanced electron mobility. This work is expected to provide guidance for full utilization of the flexible electronic properties in PbO2 and SnO2.
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Affiliation(s)
- Fengxian Ma
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Gardens Point Campus , Brisbane 4001, Queensland, Australia
| | - Yalong Jiao
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Gardens Point Campus , Brisbane 4001, Queensland, Australia
| | - Guoping Gao
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Gardens Point Campus , Brisbane 4001, Queensland, Australia
| | - Yuantong Gu
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Gardens Point Campus , Brisbane 4001, Queensland, Australia
| | - Ante Bilic
- CSIRO Data61, Molecular and Materials Modelling , Docklands 3008, Victoria, Australia
| | - Stefano Sanvito
- School of Physics, AMBER and CRANN Institute, Trinity College , Dublin 2, Ireland
| | - Aijun Du
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Gardens Point Campus , Brisbane 4001, Queensland, Australia
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36
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Burkov AA, Kim YB. Z_{2} and Chiral Anomalies in Topological Dirac Semimetals. PHYSICAL REVIEW LETTERS 2016; 117:136602. [PMID: 27715103 DOI: 10.1103/physrevlett.117.136602] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate that topological Dirac semimetals, which possess two Dirac nodes, separated in momentum space along a rotation axis and protected by rotational symmetry, exhibit an additional quantum anomaly, distinct from the chiral anomaly. This anomaly, which we call the Z_{2} anomaly, is a consequence of the fact that the Dirac nodes in topological Dirac semimetals carry a Z_{2} topological charge. The Z_{2} anomaly refers to nonconservation of this charge in the presence of external fields due to quantum effects and has observable consequences due to its interplay with the chiral anomaly. We discuss possible implications of this for the interpretation of magnetotransport experiments on topological Dirac semimetals. We also provide a possible explanation for the magnetic field dependent angular narrowing of the negative longitudinal magnetoresistance, observed in a recent experiment on Na_{3}Bi.
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Affiliation(s)
- Anton A Burkov
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- ITMO University, Saint Petersburg 197101, Russia
| | - Yong Baek Kim
- Department of Physics and Center for Quantum Materials, University of Toronto, Toronto, Ontario M5S 1A7, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
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Aggarwal L, Gaurav A, Thakur GS, Haque Z, Ganguli AK, Sheet G. Unconventional superconductivity at mesoscopic point contacts on the 3D Dirac semimetal Cd3As2. NATURE MATERIALS 2016; 15:32-37. [PMID: 26524131 DOI: 10.1038/nmat4455] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 08/13/2015] [Indexed: 06/05/2023]
Abstract
Three-dimensional (3D) Dirac semimetals exist close to topological phase boundaries which, in principle, should make it possible to drive them into exotic new phases, such as topological superconductivity, by breaking certain symmetries. A practical realization of this idea has, however, hitherto been lacking. Here we show that the mesoscopic point contacts between pure silver (Ag) and the 3D Dirac semimetal Cd3As2 (ref. ) exhibit unconventional superconductivity with a critical temperature (onset) greater than 6 K whereas neither Cd3As2 nor Ag are superconductors. A gap amplitude of 6.5 meV is measured spectroscopically in this phase that varies weakly with temperature and survives up to a remarkably high temperature of 13 K, indicating the presence of a robust normal-state pseudogap. The observations indicate the emergence of a new unconventional superconducting phase that exists in a quantum mechanically confined region under a point contact between a Dirac semimetal and a normal metal.
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Affiliation(s)
- Leena Aggarwal
- Department of Physical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Sector 81, S. A. S. Nagar Manauli, PO 140306, India
| | - Abhishek Gaurav
- Department of Physical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Sector 81, S. A. S. Nagar Manauli, PO 140306, India
| | - Gohil S Thakur
- Department of Chemistry, Indian Institute of Technology, New Delhi 110016, India
| | - Zeba Haque
- Department of Chemistry, Indian Institute of Technology, New Delhi 110016, India
| | - Ashok K Ganguli
- Department of Chemistry, Indian Institute of Technology, New Delhi 110016, India
- Institute of Nano Science and Technology, Mohali 160064, India
| | - Goutam Sheet
- Department of Physical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Sector 81, S. A. S. Nagar Manauli, PO 140306, India
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