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Title: Observation of topological superconductivity on the surface of an iron-based superconductor

Abstract

Topological superconductors are predicted to host exotic Majorana states that obey non-Abelian statistics and can be used to implement a topological quantum computer. Most of the proposed topological superconductors are realized in difficult-to-fabricate heterostructures at very low temperatures. By using high-resolution spin-resolved and angle-resolved photoelectron spectroscopy, we find that the iron-based superconductor FeTe1–xSex (x = 0.45; superconducting transition temperature Tc = 14.5 kelvin) hosts Dirac-cone–type spin-helical surface states at the Fermi level; the surface states exhibit an s-wave superconducting gap below Tc. Thus, our study shows that the surface states of FeTe0.55Se0.45 are topologically superconducting, providing a simple and possibly high-temperature platform for realizing Majorana states.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [5]; ORCiD logo [1]
  1. Univ. of Tokyo (Japan). Inst. for Solid State Physics
  2. Princeton Univ., NJ (United States). Dept. of Physics
  3. Nanjing Univ. (China). National Lab. of Solid State Microstructures and Dept. of Physics
  4. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.
  5. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics. Beijing National Lab. for Condensed Matter Physics (BNLCP-CAS); Univ. of Chinese Academy of Sciences (CAS), Beijing (China). CAS Center for Excellence in Topological Quantum Computation
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; Ministry of Education, Culture, Sports, Science and Technology (MEXT); Japan Society for the Promotion of Science (JSPS); National Natural Science Foundation of China (NNSFC); Ministry of Science and Technology (MOST); Chinese Academy of Sciences (CAS)
OSTI Identifier:
1440897
Report Number(s):
BNL-205750-2018-JAAM
Journal ID: ISSN 0036-8075
Grant/Contract Number:  
SC0012704; 25220707; 16H02209; 16H06013; 16H00979; 11234014; 11504117; 2016YFA0401000; 2015CB921300; XDPB08-1; XDB07000000
Resource Type:
Accepted Manuscript
Journal Name:
Science
Additional Journal Information:
Journal Volume: 360; Journal Issue: 6385; Journal ID: ISSN 0036-8075
Publisher:
AAAS
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 97 MATHEMATICS AND COMPUTING

Citation Formats

Zhang, Peng, Yaji, Koichiro, Hashimoto, Takahiro, Ota, Yuichi, Kondo, Takeshi, Okazaki, Kozo, Wang, Zhijun, Wen, Jinsheng, Gu, G. D., Ding, Hong, and Shin, Shik. Observation of topological superconductivity on the surface of an iron-based superconductor. United States: N. p., 2018. Web. doi:10.1126/science.aan4596.
Zhang, Peng, Yaji, Koichiro, Hashimoto, Takahiro, Ota, Yuichi, Kondo, Takeshi, Okazaki, Kozo, Wang, Zhijun, Wen, Jinsheng, Gu, G. D., Ding, Hong, & Shin, Shik. Observation of topological superconductivity on the surface of an iron-based superconductor. United States. doi:10.1126/science.aan4596.
Zhang, Peng, Yaji, Koichiro, Hashimoto, Takahiro, Ota, Yuichi, Kondo, Takeshi, Okazaki, Kozo, Wang, Zhijun, Wen, Jinsheng, Gu, G. D., Ding, Hong, and Shin, Shik. Thu . "Observation of topological superconductivity on the surface of an iron-based superconductor". United States. doi:10.1126/science.aan4596. https://www.osti.gov/servlets/purl/1440897.
@article{osti_1440897,
title = {Observation of topological superconductivity on the surface of an iron-based superconductor},
author = {Zhang, Peng and Yaji, Koichiro and Hashimoto, Takahiro and Ota, Yuichi and Kondo, Takeshi and Okazaki, Kozo and Wang, Zhijun and Wen, Jinsheng and Gu, G. D. and Ding, Hong and Shin, Shik},
abstractNote = {Topological superconductors are predicted to host exotic Majorana states that obey non-Abelian statistics and can be used to implement a topological quantum computer. Most of the proposed topological superconductors are realized in difficult-to-fabricate heterostructures at very low temperatures. By using high-resolution spin-resolved and angle-resolved photoelectron spectroscopy, we find that the iron-based superconductor FeTe1–xSex (x = 0.45; superconducting transition temperature Tc = 14.5 kelvin) hosts Dirac-cone–type spin-helical surface states at the Fermi level; the surface states exhibit an s-wave superconducting gap below Tc. Thus, our study shows that the surface states of FeTe0.55Se0.45 are topologically superconducting, providing a simple and possibly high-temperature platform for realizing Majorana states.},
doi = {10.1126/science.aan4596},
journal = {Science},
number = 6385,
volume = 360,
place = {United States},
year = {2018},
month = {3}
}

Journal Article:
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Cited by: 49 works
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Figures / Tables:

Figure 1 Figure 1: Band structure and topological superconductivity of FeTe0.5Se0.5. (A) Crystal structure of Fe(Te,Se), together with the 3D BZ and projected surface BZ. (B) In-plane BZ at kz = 0. There are two hole-like FSs at Γ and two electron-like FSs at M. The dashed circle at Γ indicates themore » hole-like band just below EF. (C) First-principles calculations on band structure along the ΓM direction, as indicated by the light blue line in (B). In the calculations, t = 100 meV, while t ~ 12 - 25 meV from experiments, largely depending on the bands (27). In this study, we focus on the small area around Γ with light blue background, where mainly dxz band is present. (D) Firstprinciples calculations on band structure along ΓM and ΓZ. The dashed box shows the SOC gap of the inverted bands. (E) Band structure projected onto the (001) surface. The topological surface states (TSS) between the bulk valence band (BVB) and bulk conduction band (BCB) is clearly shown in this plot. (F) When the temperature decreases to below Tc, the bulk bands open s-wave SC gaps, which induce the surface states to be superconducting. The spin-helical surface states thus become topologically superconducting. (The side surface is shown for convenience.)« less

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