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

Peng Zhang; Koichiro Yaji; Takahiro Hashimoto; Yuichi Ota; Takeshi Kondo; Kozo Okazaki; Zhijun Wang; Jinsheng Wen; G. D. Gu; Hong Ding; Shik Shin

doi:10.1126/science.aan4596

arXiv · 1706.05163

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

Peng Zhang·Koichiro Yaji·Takahiro Hashimoto·Yuichi Ota·Takeshi Kondo·Kozo Okazaki·Zhijun Wang·Jinsheng Wen·G. D. Gu·Hong Ding·Shik Shin

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Abstract

Topological superconductors, whose edge hosts Majorana bound states or Majorana fermions that obey non-Abelian statistics, can be used for low-decoherence quantum computations. Most of the proposed topological superconductors are realized with spin-helical states through proximity effect to BCS superconductors. However, such approaches are difficult for further studies and applications because of the low transition temperatures and complicated hetero-structures. Here by using high-resolution spin-resolved and angle-resolved photoelectron spectroscopy, we discover that the iron-based superconductor FeTe1-xSex (x = 0.45, Tc = 14.5 K) hosts Dirac-cone type spin-helical surface states at Fermi level, which open an s-wave SC gap below Tc. Our study proves that the surface states of FeTe0.55Se0.45 are 2D topologically superconducting, and thus provides a simple and possibly high-Tc platform for realizing Majorana fermions.

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Peng Zhang, Koichiro Yaji, Takahiro Hashimoto, Yuichi Ota, Takeshi Kondo, Kozo Okazaki, Zhijun Wang, Jinsheng Wen, G. D. Gu, Hong Ding, Shik Shin. 2017-06-16. Observation of topological superconductivity on the surface of an iron-based superconductor. https://doi.org/10.1126/science.aan4596

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