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Chou F, Buchanan M, McDonald M, Westwood M, Huang C. Narrative Themes of Chinese Canadian Intergenerational Trauma: Parental Experiences. Counselling Psychology Quarterly 2023. [DOI: 10.1080/09515070.2022.2160431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- F. Chou
- Educational Psychology and Leadership Studies, Faculty of Education, University of Victoria
| | - M. Buchanan
- Educational and Counselling Psychology, and Special Education, Faculty of Education, University of British Columbia
| | - M. McDonald
- Counselling Psychology, School of Graduate Studies, Trinity Western University
| | - M. Westwood
- Educational and Counselling Psychology, and Special Education, Faculty of Education, University of British Columbia
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2
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Do SH, Lee CH, Kihara T, Choi YS, Yoon S, Kim K, Cheong H, Chen WT, Chou F, Nojiri H, Choi KY. Randomly Hopping Majorana Fermions in the Diluted Kitaev System α-Ru_{0.8}Ir_{0.2}Cl_{3}. Phys Rev Lett 2020; 124:047204. [PMID: 32058744 DOI: 10.1103/physrevlett.124.047204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 10/09/2019] [Indexed: 06/10/2023]
Abstract
dc and ac magnetic susceptibility, magnetization, specific heat, and Raman scattering measurements are combined to probe low-lying spin excitations in α-Ru_{1-x}Ir_{x}Cl_{3} (x≈0.2), which realizes a disordered spin liquid. At intermediate energies (ℏω>3 meV), Raman spectroscopy evidences linearly ω-dependent Majorana-like excitations, obeying Fermi statistics. This points to robustness of a Kitaev paramagnetic state under spin vacancies. At low energies below 3 meV, we observe power-law dependences and quantum-critical-like scalings of the thermodynamic quantities, implying the presence of a weakly divergent low-energy density of states. This scaling phenomenology is interpreted in terms of the random hoppings of Majorana fermions. Our results demonstrate an emergent hierarchy of spin excitations in a diluted Kitaev honeycomb system subject to spin vacancies and bond randomness.
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Affiliation(s)
- Seung-Hwan Do
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - C H Lee
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - T Kihara
- Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8577, Japan
| | - Y S Choi
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Sungwon Yoon
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Kangwon Kim
- Department of Physics, Sogang University, Seoul 04107, Republic of Korea
| | - Hyeonsik Cheong
- Department of Physics, Sogang University, Seoul 04107, Republic of Korea
| | - Wei-Tin Chen
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10622, Taiwan
| | - H Nojiri
- Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8577, Japan
| | - Kwang-Yong Choi
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
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3
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Ahmed B, Jo H, Yoon SW, Choi K, Chen W, Chou F, Ok KM. Mixed Transition Metal (Oxy)fluoride Paramagnet Chains: Synthesis, Structure, and Characterization. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201900509] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Belal Ahmed
- Department of Chemistry Chung‐Ang University 06974 Seoul Republic of Korea
| | - Hongil Jo
- Department of Chemistry Chung‐Ang University 06974 Seoul Republic of Korea
| | - Sung Won Yoon
- Department of Physics Chung‐Ang University 06974 Seoul Republic of Korea
| | - Kwang‐Yong Choi
- Department of Physics Chung‐Ang University 06974 Seoul Republic of Korea
| | - Wei‐tin Chen
- Center for Condensed Matter Sciences National Taiwan University 10617 Taipei Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter Sciences National Taiwan University 10617 Taipei Taiwan
- National Synchrotron Radiation Research Center 30076 Hsinchu Taiwan
- Taiwan Consortium of Emergent Crystalline Materials Ministry of Science and Technology 10622 Taipei Taiwan
| | - Kang Min Ok
- Department of Chemistry Sogang University 04107 Seoul Republic of Korea
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Choi YS, Lee CH, Lee S, Yoon S, Lee WJ, Park J, Ali A, Singh Y, Orain JC, Kim G, Rhyee JS, Chen WT, Chou F, Choi KY. Exotic Low-Energy Excitations Emergent in the Random Kitaev Magnet Cu_{2}IrO_{3}. Phys Rev Lett 2019; 122:167202. [PMID: 31075021 DOI: 10.1103/physrevlett.122.167202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 02/17/2019] [Indexed: 06/09/2023]
Abstract
We report on magnetization M(H), dc and ac magnetic susceptibility χ(T), specific heat C_{m}(T) and muon spin relaxation (μSR) measurements of the Kitaev honeycomb iridate Cu_{2}IrO_{3} with quenched disorder. In spite of the chemical disorders, we find no indication of spin glass down to 260 mK from the C_{m}(T) and μSR data. Furthermore, a persistent spin dynamics observed by the zero-field muon spin relaxation evidences an absence of static magnetism. The remarkable observation is a scaling relation of χ[H,T] and M[H,T] in H/T with the scaling exponent α=0.26-0.28, expected from bond randomness. However, C_{m}[H,T]/T disobeys the predicted universal scaling law, pointing towards the presence of additional low-lying excitations on the background of bond-disordered spin liquid. Our results signify a many-faceted impact of quenched disorder in a Kitaev spin system due to its peculiar bond character.
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Affiliation(s)
- Y S Choi
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - C H Lee
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - S Lee
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Sungwon Yoon
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - W-J Lee
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - J Park
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Anzar Ali
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli 140306, India
| | - Yogesh Singh
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli 140306, India
| | - Jean-Christophe Orain
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Gareoung Kim
- Department of Applied Physics, Kyung Hee University, Yongin 17104, Republic of Korea
| | - Jong-Soo Rhyee
- Department of Applied Physics, Kyung Hee University, Yongin 17104, Republic of Korea
| | - Wei-Tin Chen
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
- Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10622, Taiwan
| | - Kwang-Yong Choi
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea
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5
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Li Y, Wang T, Wang H, Li Z, Chen Y, West D, Sankar R, Ulaganathan RK, Chou F, Wetzel C, Xu CY, Zhang S, Shi SF. Enhanced Light Emission from the Ridge of Two-Dimensional InSe Flakes. Nano Lett 2018; 18:5078-5084. [PMID: 30021441 DOI: 10.1021/acs.nanolett.8b01940] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
InSe, a newly rediscovered two-dimensional (2D) semiconductor, possesses superior electrical and optical properties as a direct-band-gap semiconductor with high mobility from bulk to atomically thin layers and is drastically different from transition-metal dichalcogenides, in which the direct band gap only exists at the single-layer limit. However, absorption in InSe is mostly dominated by an out-of-plane dipole contribution, which results in the limited absorption of normally incident light that can only excite the in-plane dipole at resonance. To address this challenge, we have explored a unique geometric ridge state of the 2D flake without compromising the sample quality. We observed the enhanced absorption at the ridge over a broad range of excitation frequencies from photocurrent and photoluminescence (PL) measurements. In addition, we have discovered new PL peaks at low temperatures due to defect states on the ridge, which can be as much as ∼60 times stronger than the intrinsic PL peak of InSe. Interestingly, the PL of the defects is highly tunable through an external electrical field, which can be attributed to the Stark effect of the localized defects. InSe ridges thus provide new avenues for manipulating light-matter interactions and defect engineering that are vitally crucial for novel optoelectronic devices based on 2D semiconductors.
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Affiliation(s)
- Yang Li
- School of Materials Science and Engineering , Harbin Institute of Technology , Harbin 150001 , China
| | | | | | - Zhipeng Li
- School of Chemistry and Chemical Engineering , Shanghai Jiao Tong University , Shanghai 200240 , China
| | | | | | - Raman Sankar
- Institute of Physics , Academia Sinica , Nangang, Taipei , Taiwan 11529 , Taiwan
- Center for Condensed Matter Science , National Taiwan University , Taipei , Taiwan 10617 , Taiwan
| | - Rajesh K Ulaganathan
- Institute of Physics , Academia Sinica , Nangang, Taipei , Taiwan 11529 , Taiwan
- Center for Condensed Matter Science , National Taiwan University , Taipei , Taiwan 10617 , Taiwan
| | - Fangcheng Chou
- Institute of Physics , Academia Sinica , Nangang, Taipei , Taiwan 11529 , Taiwan
- Center for Condensed Matter Science , National Taiwan University , Taipei , Taiwan 10617 , Taiwan
| | | | - Cheng-Yan Xu
- School of Materials Science and Engineering , Harbin Institute of Technology , Harbin 150001 , China
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6
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Hosen MM, Dimitri K, Nandy AK, Aperis A, Sankar R, Dhakal G, Maldonado P, Kabir F, Sims C, Chou F, Kaczorowski D, Durakiewicz T, Oppeneer PM, Neupane M. Distinct multiple fermionic states in a single topological metal. Nat Commun 2018; 9:3002. [PMID: 30068909 PMCID: PMC6070493 DOI: 10.1038/s41467-018-05233-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/20/2018] [Indexed: 11/09/2022] Open
Abstract
Among the quantum materials that have recently gained interest are the topological insulators, wherein symmetry-protected surface states cross in reciprocal space, and the Dirac nodal-line semimetals, where bulk bands touch along a line in k-space. However, the existence of multiple fermion phases in a single material has not been verified yet. Using angle-resolved photoemission spectroscopy (ARPES) and first-principles electronic structure calculations, we systematically study the metallic material Hf2Te2P and discover properties, which are unique in a single topological quantum material. We experimentally observe weak topological insulator surface states and our calculations suggest additional strong topological insulator surface states. Our first-principles calculations reveal a one-dimensional Dirac crossing—the surface Dirac-node arc—along a high-symmetry direction which is confirmed by our ARPES measurements. This novel state originates from the surface bands of a weak topological insulator and is therefore distinct from the well-known Fermi arcs in semimetals. The existence of multiple topological phases in a single material, although theoretically possible, has not been verified. Here, the authors observe weak topological insulator surface states and a one-dimensional Dirac-node crossing surface state in a single metallic material Hf2Te2P.
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Affiliation(s)
- M Mofazzel Hosen
- Department of Physics, University of Central Florida, Orlando, FL, 32816, USA
| | - Klauss Dimitri
- Department of Physics, University of Central Florida, Orlando, FL, 32816, USA
| | - Ashis K Nandy
- Department of Physics and Astronomy, Uppsala University, P. O. Box 516, S-75120, Uppsala, Sweden.
| | - Alex Aperis
- Department of Physics and Astronomy, Uppsala University, P. O. Box 516, S-75120, Uppsala, Sweden.
| | - Raman Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan Institute of Physics, Academia Sinica, Taipei, 10617, Taiwan.,Institute of Physics, Academia Sinica, Taipei, 10617, Taiwan
| | - Gyanendra Dhakal
- Department of Physics, University of Central Florida, Orlando, FL, 32816, USA
| | - Pablo Maldonado
- Department of Physics and Astronomy, Uppsala University, P. O. Box 516, S-75120, Uppsala, Sweden
| | - Firoza Kabir
- Department of Physics, University of Central Florida, Orlando, FL, 32816, USA
| | - Christopher Sims
- Department of Physics, University of Central Florida, Orlando, FL, 32816, USA
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan Institute of Physics, Academia Sinica, Taipei, 10617, Taiwan
| | - Dariusz Kaczorowski
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950, Wroclaw, Poland
| | - Tomasz Durakiewicz
- Condensed Matter and Magnet Science Group, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Peter M Oppeneer
- Department of Physics and Astronomy, Uppsala University, P. O. Box 516, S-75120, Uppsala, Sweden
| | - Madhab Neupane
- Department of Physics, University of Central Florida, Orlando, FL, 32816, USA.
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7
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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8
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Walkup D, Assaf BA, Scipioni KL, Sankar R, Chou F, Chang G, Lin H, Zeljkovic I, Madhavan V. Interplay of orbital effects and nanoscale strain in topological crystalline insulators. Nat Commun 2018; 9:1550. [PMID: 29674651 PMCID: PMC5908802 DOI: 10.1038/s41467-018-03887-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 03/20/2018] [Indexed: 11/12/2022] Open
Abstract
Orbital degrees of freedom can have pronounced effects on the fundamental properties of electrons in solids. In addition to influencing bandwidths, gaps, correlation strength and dispersion, orbital effects have been implicated in generating novel electronic and structural phases. Here we show how the orbital nature of bands can result in non-trivial effects of strain on band structure. We use scanning–tunneling microscopy to study the effects of strain on the electronic structure of a heteroepitaxial thin film of a topological crystalline insulator, SnTe. By studying the effects of uniaxial strain on the band structure we find a surprising effect where strain applied in one direction has the most pronounced influence on the band structure along the perpendicular direction. Our theoretical calculations indicate that this effect arises from the orbital nature of the conduction and valence bands. Our results imply that a microscopic model capturing strain effects must include a consideration of the orbital nature of bands. The role of orbital degrees of freedom in determining the electronic structure remains obscured. Here, Walkup et al. report strain-induced band structure changes in a topological crystalline insulator SnTe, whose surprising behavior reflects the orbital nature of bands.
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Affiliation(s)
- Daniel Walkup
- Department of Physics, Boston College, Chestnut Hill, MA, 02467, USA.,National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Badih A Assaf
- Department of Physics, Boston College, Chestnut Hill, MA, 02467, USA.,Département de Physique, Ecole Normale Supérieure, PSL Research University, CNRS, Paris, 75005, France
| | - Kane L Scipioni
- Department of Physics, Boston College, Chestnut Hill, MA, 02467, USA.,Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - R Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of, Singapore, 117546, Singapore
| | - Hsin Lin
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Ilija Zeljkovic
- Department of Physics, Boston College, Chestnut Hill, MA, 02467, USA.
| | - Vidya Madhavan
- Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
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9
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Walton H, Liu D, Chou F, Klass D, Maher B, Chung J. 3:27 PM Abstract No. 84 Radiation segmentectomy vs. conventional Y-90 selective internal radiation therapy: a comparison of survival in patients treated for hepatocellular carcinoma with portal vein thrombosis. J Vasc Interv Radiol 2018. [DOI: 10.1016/j.jvir.2018.01.097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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10
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Maher B, Klass D, Chou F, Liu D, Walton H, Chung J. 3:36 PM Abstract No. 37 Retrospective analysis of 30-60μm and 50-100μm HepaSphere drug-eluting beads doxorubicin (DEBDOX) embolization in BCLC B patients with non-resectable hepatocellular carcinoma: preliminary results. J Vasc Interv Radiol 2018. [DOI: 10.1016/j.jvir.2018.01.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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11
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Wang Y, Luo G, Liu J, Sankar R, Wang NL, Chou F, Fu L, Li Z. Erratum: Observation of ultrahigh mobility surface states in a topological crystalline insulator by infrared spectroscopy. Nat Commun 2017; 8:982. [PMID: 29026090 PMCID: PMC5638947 DOI: 10.1038/s41467-017-01354-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Ying Wang
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Guoyu Luo
- College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan, 610064, China
| | - Junwei Liu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - R Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan.,Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan
| | - Nan-Lin Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Zhiqiang Li
- College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan, 610064, China.
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12
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Wang Y, Luo G, Liu J, Sankar R, Wang NL, Chou F, Fu L, Li Z. Observation of ultrahigh mobility surface states in a topological crystalline insulator by infrared spectroscopy. Nat Commun 2017; 8:366. [PMID: 28848231 PMCID: PMC5573725 DOI: 10.1038/s41467-017-00446-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 06/29/2017] [Indexed: 11/09/2022] Open
Abstract
Topological crystalline insulators possess metallic surface states protected by crystalline symmetry, which are a versatile platform for exploring topological phenomena and potential applications. However, progress in this field has been hindered by the challenge to probe optical and transport properties of the surface states owing to the presence of bulk carriers. Here, we report infrared reflectance measurements of a topological crystalline insulator, (001)-oriented Pb1−xSnxSe in zero and high magnetic fields. We demonstrate that the far-infrared conductivity is unexpectedly dominated by the surface states as a result of their unique band structure and the consequent small infrared penetration depth. Moreover, our experiments yield a surface mobility of 40,000 cm2 V−1 s−1, which is one of the highest reported values in topological materials, suggesting the viability of surface-dominated conduction in thin topological crystalline insulator crystals. These findings pave the way for exploring many exotic transport and optical phenomena and applications predicted for topological crystalline insulators. Probing optical and transport properties of the surface states in topological crystalline insulators remains a challenge. Here, Wang et al. demonstrate that the far-infrared conductivity of Pb1−xSnxSe (x = 0.23−0.25) single crystals is dominated by the surface states where carriers show a high surface mobility of 40,000 cm2 V−1 s−1.
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Affiliation(s)
- Ying Wang
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Guoyu Luo
- College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan, 610064, China
| | - Junwei Liu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - R Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan.,Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan
| | - Nan-Lin Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Zhiqiang Li
- College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan, 610064, China.
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13
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Dai W, Richardella A, Du R, Zhao W, Liu X, Liu CX, Huang SH, Sankar R, Chou F, Samarth N, Li Q. Proximity-effect-induced Superconducting Gap in Topological Surface States - A Point Contact Spectroscopy Study of NbSe 2/Bi 2Se 3 Superconductor-Topological Insulator Heterostructures. Sci Rep 2017; 7:7631. [PMID: 28794508 PMCID: PMC5550495 DOI: 10.1038/s41598-017-07990-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/03/2017] [Indexed: 11/21/2022] Open
Abstract
Proximity-effect-induced superconductivity was studied in epitaxial topological insulator Bi2Se3 thin films grown on superconducting NbSe2 single crystals. A point contact spectroscopy (PCS) method was used at low temperatures down to 40 mK. An induced superconducting gap in Bi2Se3 was observed in the spectra, which decreased with increasing Bi2Se3 layer thickness, consistent with the proximity effect in the bulk states of Bi2Se3 induced by NbSe2. At very low temperatures, an extra point contact feature which may correspond to a second energy gap appeared in the spectrum. For a 16 quintuple layer Bi2Se3 on NbSe2 sample, the bulk state gap value near the top surface is ~159 μeV, while the second gap value is ~120 μeV at 40 mK. The second gap value decreased with increasing Bi2Se3 layer thickness, but the ratio between the second gap and the bulk state gap remained about the same for different Bi2Se3 thicknesses. It is plausible that this is due to superconductivity in Bi2Se3 topological surface states induced through the bulk states. The two induced gaps in the PCS measurement are consistent with the three-dimensional bulk state and the two-dimensional surface state superconducting gaps observed in the angle-resolved photoemission spectroscopy (ARPES) measurement.
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Affiliation(s)
- Wenqing Dai
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Anthony Richardella
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Renzhong Du
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Weiwei Zhao
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Xin Liu
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - C X Liu
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Song-Hsun Huang
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Raman Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Qi Li
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA.
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14
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Neupane M, Alidoust N, Hosen MM, Zhu JX, Dimitri K, Xu SY, Dhakal N, Sankar R, Belopolski I, Sanchez DS, Chang TR, Jeng HT, Miyamoto K, Okuda T, Lin H, Bansil A, Kaczorowski D, Chou F, Hasan MZ, Durakiewicz T. Observation of the spin-polarized surface state in a noncentrosymmetric superconductor BiPd. Nat Commun 2016; 7:13315. [PMID: 27819655 PMCID: PMC5103058 DOI: 10.1038/ncomms13315] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 09/22/2016] [Indexed: 11/08/2022] Open
Abstract
Recently, noncentrosymmetric superconductor BiPd has attracted considerable research interest due to the possibility of hosting topological superconductivity. Here we report a systematic high-resolution angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES study of the normal state electronic and spin properties of BiPd. Our experimental results show the presence of a surface state at higher-binding energy with the location of Dirac point at around 700 meV below the Fermi level. The detailed photon energy, temperature-dependent and spin-resolved ARPES measurements complemented by our first-principles calculations demonstrate the existence of the spin-polarized surface states at high-binding energy. The absence of such spin-polarized surface states near the Fermi level negates the possibility of a topological superconducting behaviour on the surface. Our direct experimental observation of spin-polarized surface states in BiPd provides critical information that will guide the future search for topological superconductivity in noncentrosymmetric materials.
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Affiliation(s)
- Madhab Neupane
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
| | - Nasser Alidoust
- Joseph Henry Laboratory and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - M. Mofazzel Hosen
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
| | - Jian-Xin Zhu
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Klauss Dimitri
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
| | - Su-Yang Xu
- Joseph Henry Laboratory and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Nagendra Dhakal
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
| | - Raman Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Ilya Belopolski
- Joseph Henry Laboratory and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Daniel S. Sanchez
- Joseph Henry Laboratory and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Koji Miyamoto
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
| | - Taichi Okuda
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Dariusz Kaczorowski
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wroclaw, Poland
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - M. Zahid Hasan
- Joseph Henry Laboratory and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Tomasz Durakiewicz
- Condensed Matter and Magnet Science Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Institute of Physics, Maria Curie - Sklodowska University, 20-031 Lublin, Poland
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15
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Guan SY, Chen PJ, Chu MW, Sankar R, Chou F, Jeng HT, Chang CS, Chuang TM. Superconducting topological surface states in the noncentrosymmetric bulk superconductor PbTaSe 2. Sci Adv 2016; 2:e1600894. [PMID: 28138520 PMCID: PMC5262470 DOI: 10.1126/sciadv.1600894] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 10/20/2016] [Indexed: 05/27/2023]
Abstract
The search for topological superconductors (TSCs) is one of the most urgent contemporary problems in condensed matter systems. TSCs are characterized by a full superconducting gap in the bulk and topologically protected gapless surface (or edge) states. Within each vortex core of TSCs, there exists the zero-energy Majorana bound states, which are predicted to exhibit non-Abelian statistics and to form the basis of the fault-tolerant quantum computation. To date, no stoichiometric bulk material exhibits the required topological surface states (TSSs) at the Fermi level (EF) combined with fully gapped bulk superconductivity. We report atomic-scale visualization of the TSSs of the noncentrosymmetric fully gapped superconductor PbTaSe2. Using quasi-particle scattering interference imaging, we find two TSSs with a Dirac point at E ≅ 1.0 eV, of which the inner TSS and the partial outer TSS cross EF, on the Pb-terminated surface of this fully gapped superconductor. This discovery reveals PbTaSe2 as a promising candidate for TSC.
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Affiliation(s)
- Syu-You Guan
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Peng-Jen Chen
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
- Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan
| | - Ming-Wen Chu
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Raman Sankar
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Horng-Tay Jeng
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chia-Seng Chang
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Tien-Ming Chuang
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
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16
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Bian G, Chang TR, Sankar R, Xu SY, Zheng H, Neupert T, Chiu CK, Huang SM, Chang G, Belopolski I, Sanchez DS, Neupane M, Alidoust N, Liu C, Wang B, Lee CC, Jeng HT, Zhang C, Yuan Z, Jia S, Bansil A, Chou F, Lin H, Hasan MZ. Topological nodal-line fermions in spin-orbit metal PbTaSe2. Nat Commun 2016; 7:10556. [PMID: 26829889 PMCID: PMC4740879 DOI: 10.1038/ncomms10556] [Citation(s) in RCA: 168] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 12/28/2015] [Indexed: 11/24/2022] Open
Abstract
Topological semimetals can support one-dimensional Fermi lines or zero-dimensional Weyl points in momentum space, where the valence and conduction bands touch. While the degeneracy points in Weyl semimetals are robust against any perturbation that preserves translational symmetry, nodal lines require protection by additional crystalline symmetries such as mirror reflection. Here we report, based on a systematic theoretical study and a detailed experimental characterization, the existence of topological nodal-line states in the non-centrosymmetric compound PbTaSe2 with strong spin-orbit coupling. Remarkably, the spin-orbit nodal lines in PbTaSe2 are not only protected by the reflection symmetry but also characterized by an integer topological invariant. Our detailed angle-resolved photoemission measurements, first-principles simulations and theoretical topological analysis illustrate the physical mechanism underlying the formation of the topological nodal-line states and associated surface states for the first time, thus paving the way towards exploring the exotic properties of the topological nodal-line fermions in condensed matter systems. Nodal-line shaped bands appearing near the Fermi level host unique properties in topological matter, which has yet to be confirmed in real materials. Here, the authors report the existence of topological nodal-line states in the non-centrosymmetric single-crystalline spin-orbit semimetal PbTaSe2.
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Affiliation(s)
- Guang Bian
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA
| | - Tay-Rong Chang
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA.,Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Raman Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Su-Yang Xu
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA
| | - Hao Zheng
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA
| | - Titus Neupert
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA.,Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544, USA
| | - Ching-Kai Chiu
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
| | - Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Ilya Belopolski
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA
| | - Daniel S Sanchez
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA
| | - Madhab Neupane
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA
| | - Nasser Alidoust
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA
| | - Chang Liu
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA
| | - BaoKai Wang
- Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore.,Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Chi-Cheng Lee
- Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.,Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Chenglong Zhang
- ICQM, School of Physics, Peking University, Beijing 100871, China
| | - Zhujun Yuan
- ICQM, School of Physics, Peking University, Beijing 100871, China
| | - Shuang Jia
- ICQM, School of Physics, Peking University, Beijing 100871, China
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.,Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - M Zahid Hasan
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, New Jersey 08544, USA
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17
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Zheng H, Xu SY, Bian G, Guo C, Chang G, Sanchez DS, Belopolski I, Lee CC, Huang SM, Zhang X, Sankar R, Alidoust N, Chang TR, Wu F, Neupert T, Chou F, Jeng HT, Yao N, Bansil A, Jia S, Lin H, Hasan MZ. Atomic-Scale Visualization of Quantum Interference on a Weyl Semimetal Surface by Scanning Tunneling Microscopy. ACS Nano 2016; 10:1378-1385. [PMID: 26743693 DOI: 10.1021/acsnano.5b06807] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Weyl semimetals may open a new era in condensed matter physics, materials science, and nanotechnology after graphene and topological insulators. We report the first atomic scale view of the surface states of a Weyl semimetal (NbP) using scanning tunneling microscopy/spectroscopy. We observe coherent quantum interference patterns that arise from the scattering of quasiparticles near point defects on the surface. The measurements reveal the surface electronic structure both below and above the chemical potential in both real and reciprocal spaces. Moreover, the interference maps uncover the scattering processes of NbP's exotic surface states. Through comparison between experimental data and theoretical calculations, we further discover that the orbital and/or spin texture of the surface bands may suppress certain scattering channels on NbP. These results provide a comprehensive understanding of electronic properties on Weyl semimetal surfaces.
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Affiliation(s)
- Hao Zheng
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University , Princeton, New Jersey 08544, United States
| | - Su-Yang Xu
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University , Princeton, New Jersey 08544, United States
| | - Guang Bian
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University , Princeton, New Jersey 08544, United States
| | - Cheng Guo
- International Center for Quantum Materials, School of Physics, Peking University , Peking, China
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Daniel S Sanchez
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University , Princeton, New Jersey 08544, United States
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University , Princeton, New Jersey 08544, United States
| | - Chi-Cheng Lee
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Xiao Zhang
- International Center for Quantum Materials, School of Physics, Peking University , Peking, China
| | - Raman Sankar
- Center for Condensed Matter Sciences, National Taiwan University , Taipei 10617, Taiwan
| | - Nasser Alidoust
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University , Princeton, New Jersey 08544, United States
| | - Tay-Rong Chang
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University , Princeton, New Jersey 08544, United States
- Department of Physics, National Tsing Hua University , Hsinchu 30013, Taiwan
| | - Fan Wu
- Princeton Institute for the Science and Technology of Materials, Princeton University , 70 Prospect Avenue, Princeton, New Jersey 08540, United States
| | - Titus Neupert
- Princeton Center for Theoretical Science, Princeton University , Princeton, New Jersey 08544, United States
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University , Taipei 10617, Taiwan
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University , Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica , Taipei 11529, Taiwan
| | - Nan Yao
- Princeton Institute for the Science and Technology of Materials, Princeton University , 70 Prospect Avenue, Princeton, New Jersey 08540, United States
| | - Arun Bansil
- Department of Physics, Northeastern University , Boston, Massachusetts 02115, United States
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University , Peking, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore , 6 Science Drive 2, Singapore 117546
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University , Princeton, New Jersey 08544, United States
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18
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Xu SY, Belopolski I, Sanchez DS, Zhang C, Chang G, Guo C, Bian G, Yuan Z, Lu H, Chang TR, Shibayev PP, Prokopovych ML, Alidoust N, Zheng H, Lee CC, Huang SM, Sankar R, Chou F, Hsu CH, Jeng HT, Bansil A, Neupert T, Strocov VN, Lin H, Jia S, Hasan MZ. Experimental discovery of a topological Weyl semimetal state in TaP. Sci Adv 2015; 1:e1501092. [PMID: 26702446 PMCID: PMC4681326 DOI: 10.1126/sciadv.1501092] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 09/20/2015] [Indexed: 05/26/2023]
Abstract
Weyl semimetals are expected to open up new horizons in physics and materials science because they provide the first realization of Weyl fermions and exhibit protected Fermi arc surface states. However, they had been found to be extremely rare in nature. Recently, a family of compounds, consisting of tantalum arsenide, tantalum phosphide (TaP), niobium arsenide, and niobium phosphide, was predicted as a Weyl semimetal candidates. We experimentally realize a Weyl semimetal state in TaP. Using photoemission spectroscopy, we directly observe the Weyl fermion cones and nodes in the bulk, and the Fermi arcs on the surface. Moreover, we find that the surface states show an unexpectedly rich structure, including both topological Fermi arcs and several topologically trivial closed contours in the vicinity of the Weyl points, which provides a promising platform to study the interplay between topological and trivial surface states on a Weyl semimetal's surface. We directly demonstrate the bulk-boundary correspondence and establish the topologically nontrivial nature of the Weyl semimetal state in TaP, by resolving the net number of chiral edge modes on a closed path that encloses the Weyl node. This also provides, for the first time, an experimentally practical approach to demonstrating a bulk Weyl fermion from a surface state dispersion measured in photoemission.
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Affiliation(s)
- Su-Yang Xu
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Daniel S. Sanchez
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Chenglong Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Cheng Guo
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Guang Bian
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Zhujun Yuan
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Hong Lu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Pavel P. Shibayev
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | | | - Nasser Alidoust
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Hao Zheng
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Chi-Cheng Lee
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Raman Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Chuang-Han Hsu
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Titus Neupert
- Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544, USA
| | - Vladimir N. Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - M. Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
- Princeton Center for Complex Materials, Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, NJ 08544, USA
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19
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Zeljkovic I, Walkup D, Assaf BA, Scipioni KL, Sankar R, Chou F, Madhavan V. Strain engineering Dirac surface states in heteroepitaxial topological crystalline insulator thin films. Nat Nanotechnol 2015; 10:849-853. [PMID: 26301903 DOI: 10.1038/nnano.2015.177] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 07/13/2015] [Indexed: 06/04/2023]
Abstract
The unique crystalline protection of the surface states in topological crystalline insulators has led to a series of predictions of strain-generated phenomena, from the appearance of pseudo-magnetic fields and helical flat bands to the tunability of Dirac surface states by strain that may be used to construct 'straintronic' nanoswitches. However, the practical realization of this exotic phenomenology via strain engineering is experimentally challenging and is yet to be achieved. Here, we have designed an experiment to not only generate and measure strain locally, but also to directly measure the resulting effects on Dirac surface states. We grew heteroepitaxial thin films of topological crystalline insulator SnTe in situ and measured them using high-resolution scanning tunnelling microscopy to determine picoscale changes in the atomic positions, which reveal regions of both tensile and compressive strain. Simultaneous Fourier-transform scanning tunnelling spectroscopy was then used to determine the effects of strain on the Dirac electrons. We find that strain continuously tunes the momentum space position of the Dirac points, consistent with theoretical predictions. Our work demonstrates the fundamental mechanism necessary for using topological crystalline insulators in strain-based applications.
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Affiliation(s)
- Ilija Zeljkovic
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Daniel Walkup
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Badih A Assaf
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Kane L Scipioni
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - R Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan, Republic of China
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Vidya Madhavan
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
- Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
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20
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Bawden L, Riley JM, Kim CH, Sankar R, Monkman EJ, Shai DE, Wei HI, Lochocki EB, Wells JW, Meevasana W, Kim TK, Hoesch M, Ohtsubo Y, Le Fèvre P, Fennie CJ, Shen KM, Chou F, King PDC. Hierarchical spin-orbital polarization of a giant Rashba system. Sci Adv 2015; 1:e1500495. [PMID: 26601268 PMCID: PMC4643772 DOI: 10.1126/sciadv.1500495] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 06/16/2015] [Indexed: 06/02/2023]
Abstract
The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization. Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration. This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.
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Affiliation(s)
- Lewis Bawden
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, UK
| | - Jonathan M. Riley
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, UK
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - Choong H. Kim
- School of Applied & Engineering Physics, Cornell University, Ithaca, NY 14853, USA
| | - Raman Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Eric J. Monkman
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - Daniel E. Shai
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - Haofei I. Wei
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - Edward B. Lochocki
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | - Justin W. Wells
- Department of Physics, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Worawat Meevasana
- School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
- NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - Timur K. Kim
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - Moritz Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - Yoshiyuki Ohtsubo
- Synchrotron SOLEIL, CNRS-CEA, L’Orme des Merisiers, Saint-Aubin-BP48, 91192 Gif-sur-Yvette, France
| | - Patrick Le Fèvre
- Synchrotron SOLEIL, CNRS-CEA, L’Orme des Merisiers, Saint-Aubin-BP48, 91192 Gif-sur-Yvette, France
| | - Craig J. Fennie
- School of Applied & Engineering Physics, Cornell University, Ithaca, NY 14853, USA
| | - Kyle M. Shen
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Phil D. C. King
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, UK
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21
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Xu SY, Belopolski I, Alidoust N, Neupane M, Bian G, Zhang C, Sankar R, Chang G, Yuan Z, Lee CC, Huang SM, Zheng H, Ma J, Sanchez DS, Wang B, Bansil A, Chou F, Shibayev PP, Lin H, Jia S, Hasan MZ. Discovery of a Weyl fermion semimetal and topological Fermi arcs. Science 2015; 349:613-7. [DOI: 10.1126/science.aaa9297] [Citation(s) in RCA: 2400] [Impact Index Per Article: 266.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 07/06/2015] [Indexed: 11/02/2022]
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22
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Zeljkovic I, Okada Y, Serbyn M, Sankar R, Walkup D, Zhou W, Liu J, Chang G, Wang YJ, Hasan MZ, Chou F, Lin H, Bansil A, Fu L, Madhavan V. Dirac mass generation from crystal symmetry breaking on the surfaces of topological crystalline insulators. Nat Mater 2015; 14:318-324. [PMID: 25686261 DOI: 10.1038/nmat4215] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 01/08/2015] [Indexed: 06/04/2023]
Abstract
The tunability of topological surface states and controllable opening of the Dirac gap are of fundamental and practical interest in the field of topological materials. In the newly discovered topological crystalline insulators (TCIs), theory predicts that the Dirac node is protected by a crystalline symmetry and that the surface state electrons can acquire a mass if this symmetry is broken. Recent studies have detected signatures of a spontaneously generated Dirac gap in TCIs; however, the mechanism of mass formation remains elusive. In this work, we present scanning tunnelling microscopy (STM) measurements of the TCI Pb1-xSnxSe for a wide range of alloy compositions spanning the topological and non-topological regimes. The STM topographies reveal a symmetry-breaking distortion on the surface, which imparts mass to the otherwise massless Dirac electrons-a mechanism analogous to the long sought-after Higgs mechanism in particle physics. Interestingly, the measured Dirac gap decreases on approaching the trivial phase, whereas the magnitude of the distortion remains nearly constant. Our data and calculations reveal that the penetration depth of Dirac surface states controls the magnitude of the Dirac mass. At the limit of the critical composition, the penetration depth is predicted to go to infinity, resulting in zero mass, consistent with our measurements. Finally, we discover the existence of surface states in the non-topological regime, which have the characteristics of gapped, double-branched Dirac fermions and could be exploited in realizing superconductivity in these materials.
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Affiliation(s)
- Ilija Zeljkovic
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Yoshinori Okada
- 1] Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA [2] WPI-AIMR, Tohoku University, Sendai 980-8577, Japan
| | - Maksym Serbyn
- 1] Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA [2] Department of Physics, University of California, Berkeley, California 94720-7300, USA
| | - R Sankar
- 1] Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan [2] Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Daniel Walkup
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Wenwen Zhou
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Junwei Liu
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Guoqing Chang
- Graphene Research Centre and Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Yung Jui Wang
- Department of Physics, Northeastern University, Boston, Massachusetts 02115 USA
| | - M Zahid Hasan
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Hsin Lin
- Graphene Research Centre and Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, Massachusetts 02115 USA
| | - Liang Fu
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Vidya Madhavan
- 1] Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA [2] Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
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23
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Liu X, Wang YJ, Barbiellini B, Hafiz H, Basak S, Liu J, Richardson T, Shu G, Chou F, Weng TC, Nordlund D, Sokaras D, Moritz B, Devereaux TP, Qiao R, Chuang YD, Bansil A, Hussain Z, Yang W. Why LiFePO4is a safe battery electrode: Coulomb repulsion induced electron-state reshuffling upon lithiation. Phys Chem Chem Phys 2015; 17:26369-77. [DOI: 10.1039/c5cp04739k] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A combined spectroscopic and theoretical study clarifies the electron states associated with the intrinsic safety of LiFePO4electrodes.
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24
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Neupane M, Xu SY, Sankar R, Alidoust N, Bian G, Liu C, Belopolski I, Chang TR, Jeng HT, Lin H, Bansil A, Chou F, Hasan MZ. Observation of a three-dimensional topological Dirac semimetal phase in high-mobility Cd3As2. Nat Commun 2014; 5:3786. [PMID: 24807399 DOI: 10.1038/ncomms4786] [Citation(s) in RCA: 295] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 04/02/2014] [Indexed: 11/10/2022] Open
Abstract
Symmetry-broken three-dimensional (3D) topological Dirac semimetal systems with strong spin-orbit coupling can host many exotic Hall-like phenomena and Weyl fermion quantum transport. Here, using high-resolution angle-resolved photoemission spectroscopy, we performed systematic electronic structure studies on Cd3As2, which has been predicted to be the parent material, from which many unusual topological phases can be derived. We observe a highly linear bulk band crossing to form a 3D dispersive Dirac cone projected at the Brillouin zone centre by studying the (001)-cleaved surface. Remarkably, an unusually high in-plane Fermi velocity up to 1.5×10(6) ms(-1) is observed in our samples, where the mobility is known up to 40,000 cm2 V(-1) s(-1), suggesting that Cd3As2 can be a promising candidate as an anisotropic-hypercone (three-dimensional) high spin-orbit analogue of 3D graphene. Our discovery of the Dirac-like bulk topological semimetal phase in Cd3As2 opens the door for exploring higher dimensional spin-orbit Dirac physics in a real material.
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Affiliation(s)
- Madhab Neupane
- 1] Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA [2]
| | - Su-Yang Xu
- 1] Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA [2]
| | - Raman Sankar
- 1] Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan [2]
| | - Nasser Alidoust
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Guang Bian
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Chang Liu
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Ilya Belopolski
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Horng-Tay Jeng
- 1] Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan [2] Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Hsin Lin
- Graphene Research Centre, Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - M Zahid Hasan
- 1] Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA [2] Princeton Center for Complex Materials, Princeton University, Princeton, New Jersey 08544, USA
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25
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Okada Y, Serbyn M, Lin H, Walkup D, Zhou W, Dhital C, Neupane M, Xu S, Wang YJ, Sankar R, Chou F, Bansil A, Hasan MZ, Wilson SD, Fu L, Madhavan V. Observation of Dirac Node Formation and Mass Acquisition in a Topological Crystalline Insulator. Science 2013; 341:1496-9. [DOI: 10.1126/science.1239451] [Citation(s) in RCA: 235] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Yoshinori Okada
- Department of Physics, Boston College, Chestnut Hill, MA 02467, USA
- World Premier International–Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Maksym Serbyn
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139,USA
| | - Hsin Lin
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Daniel Walkup
- Department of Physics, Boston College, Chestnut Hill, MA 02467, USA
| | - Wenwen Zhou
- Department of Physics, Boston College, Chestnut Hill, MA 02467, USA
| | - Chetan Dhital
- Department of Physics, Boston College, Chestnut Hill, MA 02467, USA
| | - Madhab Neupane
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Suyang Xu
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Yung Jui Wang
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - R. Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - M. Zahid Hasan
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544, USA
- Princeton Center for Complex Materials, Princeton University, Princeton, NJ 08544, USA
| | | | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139,USA
| | - Vidya Madhavan
- Department of Physics, Boston College, Chestnut Hill, MA 02467, USA
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26
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Liu X, Liu J, Qiao R, Yu Y, Li H, Suo L, Hu YS, Chuang YD, Shu G, Chou F, Weng TC, Nordlund D, Sokaras D, Wang YJ, Lin H, Barbiellini B, Bansil A, Song X, Liu Z, Yan S, Liu G, Qiao S, Richardson TJ, Prendergast D, Hussain Z, de Groot FMF, Yang W. Phase Transformation and Lithiation Effect on Electronic Structure of LixFePO4: An In-Depth Study by Soft X-ray and Simulations. J Am Chem Soc 2012; 134:13708-15. [DOI: 10.1021/ja303225e] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Ruimin Qiao
- School of Physics, Shandong University, Jinan, Shandong, 250100, China
| | - Yan Yu
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Hong Li
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100080, China
| | - Liumin Suo
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100080, China
| | - Yong-sheng Hu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100080, China
| | | | - Guojiun Shu
- Center for Condensed Matter
Sciences, National Taiwan University, Taipei,
10617 Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter
Sciences, National Taiwan University, Taipei,
10617 Taiwan
| | - Tsu-Chien Weng
- Stanford Synchrotron
Radiation
Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Dennis Nordlund
- Stanford Synchrotron
Radiation
Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Dimosthenis Sokaras
- Stanford Synchrotron
Radiation
Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Yung Jui Wang
- Department of Physics, Northeastern University, Boston, Massachusetts 02115,
United States
| | - Hsin Lin
- Department of Physics, Northeastern University, Boston, Massachusetts 02115,
United States
| | - Bernardo Barbiellini
- Department of Physics, Northeastern University, Boston, Massachusetts 02115,
United States
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, Massachusetts 02115,
United States
| | | | | | - Shishen Yan
- School of Physics, Shandong University, Jinan, Shandong, 250100, China
| | | | - Shan Qiao
- Laboratory
of Advanced Materials,
Department of Physics, Fudan University, Shanghai, 200438, China
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27
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Abstract
BACKGROUND AND AIMS Hepatolithiasis is prevalent in southeast Asia and presents a difficult management problem. Acute repeated episodes of cholangitis are frequently manifested in patients with hepatolithiasis. Without proper treatment, such infection can lead to liver abscess, secondary biliary cirrhosis, portal hypertension, and death from sepsis or hepatic failure. In addition to clearance of the stones and relief of bile stasis either by surgery or by interventional radiologic manipulation, effective antimicrobial therapy also plays a crucial role in the treatment of patients with hepatolithiasis. The aim of this study is to clarify the bacteriology in hepatolithiasis and to provide the information for an appropriate antimicrobial choice. METHODS From July 1993 to June 1996, 150 patients with hepatolithiasis underwent surgical intervention. Bile specimens were routinely obtained by syringe aspiration from common bile duct. The syringe was immediately capped, and the bile was subsequently cultured for both aerobes and anaerobes. RESULTS Bacteria were present in the bile of all patients. The bacteria most frequently found were gram-negative bacteria such as Klebsiella sp, Escherichia coli, and Pseudomonas sp, and the gram-positive Enterococcus sp. Bacteroides sp were the most frequently found anaerobes. CONCLUSIONS This study demonstrated the close relationship between acute cholangitis in hepatolithiasis and enteric bacteria and also displayed the detailed antibiotic sensitivity results. Armed with this fruitful information, we believe the antibiotic treatment for acute cholangitis in hepatolithiasis should first aim at enteric bacteria and be adjusted later according to the results of bacteriologic cultures and clinical situation to achieve an effective microbial control.
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Affiliation(s)
- S Sheen-Chen
- Division of General Surgery, Department of Surgery, Chang Gung Memorial Hospital, Kaohsiung, College of Medicine, Chang Gung University, Taiwan
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28
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Kertes PJ, Peyman GA, Chou F, Meffert S, Conway MD. The use of tissue plasminogen activator in silicone oil-filled eyes. Can J Ophthalmol 1998; 33:28-9. [PMID: 9513769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- P J Kertes
- LSU Eye Center, New Orleans, LA 70112-2234, USA
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29
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Kibler RF, Fritz RB, Chou F, Peacocke NY, Brown NM, McFarlin DE. Immune response of Lewis rats to peptide C1 (residues 68-88) of guinea pig and rat myelin basic proteins. J Exp Med 1977; 146:1323-31. [PMID: 72777 PMCID: PMC2180966 DOI: 10.1084/jem.146.5.1323] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Peptide C1 (residues 68-88) from GP and rat BP differ by a single amino acid interchange at residue 79. This residue is serine in GP C1 and threonine in rat C1. GP C1 was encephalitogenic in Le rats at doses as low as 15 ng. Rat C1 was encephalitogenic at doses of 1,500 ng or greater. LNC from rats challenged with 25 X 10(-4) micronmol of GP C1 and 250 X 10(-4) micronmol of rat C1 showed a proliferative response in vitro to both peptides, but in each instance the magnitude of the response was greater to the GP peptide. GP C1 also induced higher levels of circulating antibodies at 25 X 10(-4) micronmol, but the specificity of antibodies produced by the two peptides was the same. These results have been interpreted as indicating that the presence of serine at position 79 in GP C1 results in the stimulation of greater numbers of T cells involved in (a) the induction of EAE, (b) the in vitro proliferative response and (c) helper function in antibody production.
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30
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Abstract
A series of 15 2,5-diaziridinyl-3,6-bis(alkylamino)-1,4-benzoquinone derivatives was synthesized and evaluated as central nervous system antitumor agents in the murine intracerebral L1210 and ependymoblastoma brain tumor systems. Intraperitoneal activity was evaluted in the leukemia L1210, P388, and B16 melanocarcinoma tumor models. The more hydrophilic hydroxyalkylamino compounds were the most effective in the intraperitoneal ascites systems (L1210, P388) with the dihydroxypropylamino (18) and hydroxyethylamino (17) analogues producing long-term survivors. The simple, more lipophilic mono- and dialkylamino derivatives were most effective in the intracerebral systems. Multiple long-term survivors were obtained with the methyl (13), ethyl (14), and dimethylamino (20) compounds in the ependymoblastoma brain tumor system. The parent amino analogue 12 was very active in several tumor models. The relationship between structure, activity, and water solubility are discussed.
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31
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Abstract
Amino acid sequences of encephalitogenic proteins from bovine cord and rabbit brain are reported. The bovine protein contains 45 residues. The rabbit protein is identical except for two isopolar substitutions, a dipeptide and amino acid deletion. Analysis of this protein and a 140-residue myelin basic protein indicates that the smaller protein is a portion of the larger encephalitogen. The larger myelin protein contains at least two encephalitogenic sites.
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