Evidence for Helical Hinge Zero Modes in an Fe-Based Superconductor

Gray, Mason J.; Freudenstein, Josef; Zhao, Shu Yang F.; O’Connor, Ryan; Jenkins, Samuel; Kumar, Narendra; Hoek, Marcel; Kopec, Abigail; Huh, Soonsang; Taniguchi, Takashi; Watanabe, Kenji; Zhong, Ruidan; Kim, Changyoung; Gu, G. D.; Burch, K. S.

doi:10.1021/acs.nanolett.9b00844

Title: Evidence for Helical Hinge Zero Modes in an Fe-Based Superconductor

Journal Article · 03 July 2019 · Nano Letters

DOI: https://doi.org/10.1021/acs.nanolett.9b00844 · OSTI ID:1566819

^[1]; Freudenstein, Josef ^[1]; Zhao, Shu Yang F. ^[2]; O’Connor, Ryan ^[1]; Jenkins, Samuel ^[1]; Kumar, Narendra ^[1]; Hoek, Marcel ^[1]; Kopec, Abigail ^[1]; Huh, Soonsang ^[3]; Taniguchi, Takashi ^[4]; Watanabe, Kenji ^[4]; Zhong, Ruidan ^[5]; Kim, Changyoung ^[6]; Gu, G. D. ^[5]; Burch, K. S. ^[1]

Boston College, Chestnut Hill, MA (United States). Dept. of Physics
Harvard Univ., Cambridge, MA (United States). Dept. of Physics
Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
National Inst. for Materials Science, Tsukuba (Japan)
Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.
Seoul National Univ. (Korea, Republic of). Dept.of Physics and Astronomy

Combining topology and superconductivity provides a powerful tool for investigating fundamental physics as well as a route to fault-tolerant quantum computing. There is mounting evidence that the Fe-based superconductor FeTe_0.55Se_0.45 (FTS) may also be topologically nontrivial. Should the superconducting order be s^±, then FTS could be a higher order topological superconductor with helical hinge zero modes (HHZMs). To test the presence of these modes, we have fabricated normal-metal/superconductor junctions on different surfaces via 2D atomic crystal heterostructures. As expected, junctions in contact with the hinge reveal a sharp zero bias anomaly that is absent when tunneling purely into the c-axis. Additionally, the shape and suppression with temperature are consistent with highly coherent modes along the hinge and are incongruous with other origins of zero bias anomalies. Additional measurements with soft-point contacts in bulk samples with various Fe interstitial contents demonstrate the intrinsic nature of the observed mode. Thus, we provide evidence that FTS is indeed a higher order topological superconductor.

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Research Organization:: Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

Grant/Contract Number:: SC0012704

OSTI ID:: 1566819

Report Number(s):: BNL-212104-2019-JAAM

Journal Information:: Nano Letters, Vol. 19, Issue 8; ISSN 1530-6984

Publisher:: American Chemical SocietyCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 43 works

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References (53)

From (π,0) magnetic order to superconductivity with (π,π) magnetic resonance in Fe1.02Te1−xSex Liu, T. J.; Hu, J.; Qian, B. Nature Materials, Vol. 9, Issue 9 https://doi.org/10.1038/nmat2800	journal	July 2010
Pairing Mechanism in Fe-Based Superconductors Chubukov, Andrey Annual Review of Condensed Matter Physics, Vol. 3, Issue 1 https://doi.org/10.1146/annurev-conmatphys-020911-125055	journal	March 2012
Macroscopic physical properties and spin dynamics in the layered superconductor Fe 1 + δ Te 1 − x Se x Michioka, Chishiro; Ohta, Hiroto; Matsui, Mami Physical Review B, Vol. 82, Issue 6 https://doi.org/10.1103/PhysRevB.82.064506	journal	August 2010
Topological nature of the FeSe 0.5 Te 0.5 superconductor Wang, Zhijun; Zhang, P.; Xu, Gang Physical Review B, Vol. 92, Issue 11 https://doi.org/10.1103/PhysRevB.92.115119	journal	September 2015
Experimental Realization of a Three-Dimensional Topological Insulator, Bi₂Te₃ Chen, Y. L.; Analytis, J. G.; Chu, J.-H. Science, Vol. 325, Issue 5937, p. 178-181 https://doi.org/10.1126/science.1173034	journal	June 2009
High-Temperature Majorana Corner States Wang, Qiyue; Liu, Cheng-Cheng; Lu, Yuan-Ming Physical Review Letters, Vol. 121, Issue 18 https://doi.org/10.1103/PhysRevLett.121.186801	journal	October 2018
Point-contact Andreev-reflection spectroscopy in Fe(Te,Se) films: multiband superconductivity and electron-boson coupling Daghero, D.; Pecchio, P.; Ummarino, G. A. Superconductor Science and Technology, Vol. 27, Issue 12 https://doi.org/10.1088/0953-2048/27/12/124014	journal	November 2014
Multiple topological states in iron-based superconductors Zhang, Peng; Wang, Zhijun; Wu, Xianxin Nature Physics, Vol. 15, Issue 1 https://doi.org/10.1038/s41567-018-0280-z	journal	September 2018
London penetration depth and superfluid density of single-crystalline Fe 1 + y ( Te 1 − x Se x ) and Fe 1 + y ( Te 1 − x S x ) Kim, H.; Martin, C.; Gordon, R. T. Physical Review B, Vol. 81, Issue 18 https://doi.org/10.1103/PhysRevB.81.180503	journal	May 2010
Observation of McMillan-Rowell like oscillations in underdoped YBa 2 Cu 3 O y junctions oriented along the node of the d -wave order parameter Shkedy, L.; Aronov, P.; Koren, G. Physical Review B, Vol. 69, Issue 13 https://doi.org/10.1103/PhysRevB.69.132507	journal	April 2004
Excess conductance of superconductor-semiconductor interfaces due to phase conjugation between electrons and holes van Wees, B. J.; de Vries, P.; Magnée, P. Physical Review Letters, Vol. 69, Issue 3 https://doi.org/10.1103/PhysRevLett.69.510	journal	July 1992
McMillan–Rowell oscillations observed in c-axis Au/Bi2Sr2CaCu2O8+δ junctions Chang, Hyun-Sik; Bae, Myung-Ho; Lee, Hu-Jong Physica C: Superconductivity, Vol. 408-410 https://doi.org/10.1016/j.physc.2004.03.084	journal	August 2004
Kondo effect in an integer-spin quantum dot Sasaki, S.; De Franceschi, S.; Elzerman, J. M. Nature, Vol. 405, Issue 6788 https://doi.org/10.1038/35015509	journal	June 2000
Anisotropic fluctuations and quasiparticle excitations in FeSe 0.5 Te 0.5 Serafin, A.; Coldea, A. I.; Ganin, A. Y. Physical Review B, Vol. 82, Issue 10 https://doi.org/10.1103/PhysRevB.82.104514	journal	September 2010
Observation of higher-order topological acoustic states protected by generalized chiral symmetry Ni, Xiang; Weiner, Matthew; Alù, Andrea Nature Materials, Vol. 18, Issue 2 https://doi.org/10.1038/s41563-018-0252-9	journal	December 2018
Acoustic higher-order topological insulator on a kagome lattice Xue, Haoran; Yang, Yahui; Gao, Fei Nature Materials, Vol. 18, Issue 2 https://doi.org/10.1038/s41563-018-0251-x	journal	December 2018
Quantum Hall effect based on Weyl orbits in Cd3As2 Zhang, Cheng; Zhang, Yi; Yuan, Xiang Nature, Vol. 565, Issue 7739 https://doi.org/10.1038/s41586-018-0798-3	journal	December 2018
Andreev–Saint-James reflections: A probe of cuprate superconductors Deutscher, Guy Reviews of Modern Physics, Vol. 77, Issue 1 https://doi.org/10.1103/RevModPhys.77.109	journal	March 2005
Helical Hinge Majorana Modes in Iron-Based Superconductors Zhang, Rui-Xing; Cole, William S.; Das Sarma, S. Physical Review Letters, Vol. 122, Issue 18 https://doi.org/10.1103/PhysRevLett.122.187001	journal	May 2019
Transition from metallic to tunneling regimes in superconducting microconstrictions: Excess current, charge imbalance, and supercurrent conversion Blonder, G. E.; Tinkham, M.; Klapwijk, T. M. Physical Review B, Vol. 25, Issue 7 https://doi.org/10.1103/PhysRevB.25.4515	journal	April 1982
Spin liquids in frustrated magnets Balents, Leon Nature, Vol. 464, Issue 7286 https://doi.org/10.1038/nature08917	journal	March 2010
Weyl and Dirac semimetals in three-dimensional solids Armitage, N. P.; Mele, E. J.; Vishwanath, Ashvin Reviews of Modern Physics, Vol. 90, Issue 1 https://doi.org/10.1103/RevModPhys.90.015001	journal	January 2018
Conductance Spectroscopy of Exfoliated Thin Flakes of Nb _x Bi ₂ Se ₃ Kurter, C.; Finck, A. D. K.; Huemiller, E. D. Nano Letters, Vol. 19, Issue 1 https://doi.org/10.1021/acs.nanolett.8b02954	journal	November 2018
Robust and Clean Majorana Zero Mode in the Vortex Core of High-Temperature Superconductor ( Li 0.84 Fe 0.16 ) OHFeSe Liu, Qin; Chen, Chen; Zhang, Tong Physical Review X, Vol. 8, Issue 4 https://doi.org/10.1103/PhysRevX.8.041056	journal	December 2018
Edge states and determination of pairing symmetry in superconducting Sr 2 RuO 4 Sengupta, K.; Kwon, Hyok-Jon; M. Yakovenko, Victor Physical Review B, Vol. 65, Issue 10 https://doi.org/10.1103/PhysRevB.65.104504	journal	February 2002
Symmetry and Topology in Superconductors –Odd-Frequency Pairing and Edge States– Tanaka, Yukio; Sato, Masatoshi; Nagaosa, Naoto Journal of the Physical Society of Japan, Vol. 81, Issue 1 https://doi.org/10.1143/JPSJ.81.011013	journal	January 2012
Effect of magnetic field on impurity bound states in high- T c superconductors Samokhin, K. V.; Walker, M. B. Physical Review B, Vol. 64, Issue 2 https://doi.org/10.1103/PhysRevB.64.024507	journal	June 2001
Andreev bound states in high- T _c superconducting junctions Löfwander, T.; Shumeiko, V. S.; Wendin, G. Superconductor Science and Technology, Vol. 14, Issue 5 https://doi.org/10.1088/0953-2048/14/5/201	journal	April 2001
Anisotropic structure of the order parameter in FeSe0.45Te0.55 revealed by angle-resolved specific heat Zeng, B.; Mu, G.; Luo, H. Q. Nature Communications, Vol. 1, Issue 1 https://doi.org/10.1038/ncomms1115	journal	November 2010
FeTe 0.55 Se 0.45 : A multiband superconductor in the clean and dirty limit Homes, C. C.; Dai, Y. M.; Wen, J. S. Physical Review B, Vol. 91, Issue 14 https://doi.org/10.1103/PhysRevB.91.144503	journal	April 2015
Evidence for a cos ( 4 φ ) Modulation of the Superconducting Energy Gap of Optimally Doped FeTe 0.6 Se 0.4 Single Crystals Using Laser Angle-Resolved Photoemission Spectroscopy Okazaki, K.; Ito, Y.; Ota, Y. Physical Review Letters, Vol. 109, Issue 23 https://doi.org/10.1103/PhysRevLett.109.237011	journal	December 2012
Higher-order topology in bismuth Schindler, Frank; Wang, Zhijun; Vergniory, Maia G. Nature Physics, Vol. 14, Issue 9 https://doi.org/10.1038/s41567-018-0224-7	journal	July 2018
Proximity-induced high-temperature superconductivity in the topological insulators Bi2Se3 and Bi2Te3 Zareapour, Parisa; Hayat, Alex; Zhao, Shu Yang F. Nature Communications, Vol. 3, Issue 1 https://doi.org/10.1038/ncomms2042	journal	January 2012
Epitaxy of advanced nanowire quantum devices Gazibegovic, Sasa; Car, Diana; Zhang, Hao Nature, Vol. 548, Issue 7668 https://doi.org/10.1038/nature23468	journal	August 2017
Doppler Shift of the Andreev Bound States at the YBCO Surface Aprili, M.; Badica, E.; Greene, L. H. Physical Review Letters, Vol. 83, Issue 22 https://doi.org/10.1103/PhysRevLett.83.4630	journal	November 1999
Quantum perfect crossed Andreev reflection in top-gated quantum anomalous Hall insulator–superconductor junctions Zhang, Ying-Tao; Hou, Zhe; Xie, X. C. Physical Review B, Vol. 95, Issue 24 https://doi.org/10.1103/PhysRevB.95.245433	journal	June 2017
Majorana Corner Modes in a High-Temperature Platform Yan, Zhongbo; Song, Fei; Wang, Zhong Physical Review Letters, Vol. 121, Issue 9 https://doi.org/10.1103/PhysRevLett.121.096803	journal	August 2018
Reflection-Symmetric Second-Order Topological Insulators and Superconductors Langbehn, Josias; Peng, Yang; Trifunovic, Luka Physical Review Letters, Vol. 119, Issue 24 https://doi.org/10.1103/PhysRevLett.119.246401	journal	December 2017
( d − 2 ) -Dimensional Edge States of Rotation Symmetry Protected Topological States Song, Zhida; Fang, Zhong; Fang, Chen Physical Review Letters, Vol. 119, Issue 24 https://doi.org/10.1103/PhysRevLett.119.246402	journal	December 2017
Unconventional s-Wave Superconductivity in Fe(Se,Te) Hanaguri, T.; Niitaka, S.; Kuroki, K. Science, Vol. 328, Issue 5977 https://doi.org/10.1126/science.1187399	journal	April 2010
Non-Abelian anyons and topological quantum computation Nayak, Chetan; Simon, Steven H.; Stern, Ady Reviews of Modern Physics, Vol. 80, Issue 3 https://doi.org/10.1103/RevModPhys.80.1083	journal	September 2008
Doppler shift of zero energy Andreev bound state Tanaka, Y. Physica B: Condensed Matter, Vol. 329-333 https://doi.org/10.1016/S0921-4526(02)02370-0	journal	May 2003
Exponential protection of zero modes in Majorana islands Albrecht, S. M.; Higginbotham, A. P.; Madsen, M. Nature, Vol. 531, Issue 7593 https://doi.org/10.1038/nature17162	journal	March 2016
Isotropic superconducting gaps with enhanced pairing on electron Fermi surfaces in FeTe 0.55 Se 0.45 Miao, H.; Richard, P.; Tanaka, Y. Physical Review B, Vol. 85, Issue 9 https://doi.org/10.1103/PhysRevB.85.094506	journal	March 2012
Observation of topological superconductivity on the surface of an iron-based superconductor Zhang, Peng; Yaji, Koichiro; Hashimoto, Takahiro Science, Vol. 360, Issue 6385 https://doi.org/10.1126/science.aan4596	journal	March 2018
Quantized electric multipole insulators Benalcazar, Wladimir A.; Bernevig, B. Andrei; Hughes, Taylor L. Science, Vol. 357, Issue 6346 https://doi.org/10.1126/science.aah6442	journal	July 2017
Anisotropic superconducting properties of single-crystalline FeSe 0.5 Te 0.5 Bendele, M.; Weyeneth, S.; Puzniak, R. Physical Review B, Vol. 81, Issue 22 https://doi.org/10.1103/PhysRevB.81.224520	journal	June 2010
Surface superconductivity in the Weyl semimetal MoTe ₂ detected by point contact spectroscopy Naidyuk, Yurii; Kvitnitskaya, Oksana; Bashlakov, Dmytro 2D Materials, Vol. 5, Issue 4 https://doi.org/10.1088/2053-1583/aad3e2	journal	August 2018
Electron temperature and tunnel coupling dependence of zero-bias and almost-zero-bias conductance peaks in Majorana nanowires Setiawan, F.; Liu, Chun-Xiao; Sau, Jay D. Physical Review B, Vol. 96, Issue 18 https://doi.org/10.1103/PhysRevB.96.184520	journal	November 2017
Evidence for Majorana bound states in an iron-based superconductor Wang, Dongfei; Kong, Lingyuan; Fan, Peng Science, Vol. 362, Issue 6412 https://doi.org/10.1126/science.aao1797	journal	August 2018
Zero Bias Conductance Peak Enhancement in Bi 2 Sr 2 CaCu 2 O 8 / Pb Tunneling Junctions Sinha, Saion; Ng, K. -W. Physical Review Letters, Vol. 80, Issue 6 https://doi.org/10.1103/PhysRevLett.80.1296	journal	February 1998
Orbital selective pairing and gap structures of iron-based superconductors Kreisel, Andreas; Andersen, Brian M.; Sprau, P. O. Physical Review B, Vol. 95, Issue 17 https://doi.org/10.1103/PhysRevB.95.174504	journal	May 2017
Zero-energy vortex bound state in the superconducting topological surface state of Fe(Se,Te) Machida, T.; Sun, Y.; Pyon, S. arXiv https://doi.org/10.48550/arxiv.1812.08995	text	January 2018

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