Topological Dirac semimetal phase in the iron-based superconductor Fe(Te,Se)

Peng Zhang; Zhijun Wang; Yukiaki Ishida; Yoshimitsu Kohama; Xianxin Wu; Koichiro Yaji; Yue Sun; Cedric Bareille; Kenta Kuroda; Takeshi Kondo; Kozo Okazaki; Koichi Kindo; Kazuki Sumida; Shilong Wu; Koji Miyamoto; Taichi Okuda; Hong Ding; G. D. Gu; Tsuyoshi Tamegai; Ronny Thomale; Takuto Kawakami; Masatoshi Sato; Shik Shin

arXiv · 1803.00845

Topological Dirac semimetal phase in the iron-based superconductor Fe(Te,Se)

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Abstract

Topological Dirac semimetals (TDSs) exhibit bulk Dirac cones protected by time reversal and crystal symmetry, as well as surface states originating from non-trivial topology. While there is a manifold possible onset of superconducting order in such systems, few observations of intrinsic superconductivity have so far been reported for TDSs. We observe evidence for a TDS phase in FeTe$_{1-x}$Se$_x$ ($x$ = 0.45), one of the high transition temperature ($T_c$) iron-based superconductors. In angle-resolved photoelectron spectroscopy (ARPES) and transport experiments, we find spin-polarized states overlapping with the bulk states on the (001) surface, and linear magnetoresistance (MR) starting from 6 T. Combined, this strongly suggests the existence of a TDS phase, which is confirmed by theoretical calculations. In total, the topological electronic states in Fe(Te,Se) provide a promising high $T_c$ platform to realize multiple topological superconducting phases.

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Peng Zhang, Zhijun Wang, Yukiaki Ishida, Yoshimitsu Kohama, Xianxin Wu, Koichiro Yaji, Yue Sun, Cedric Bareille, Kenta Kuroda, Takeshi Kondo, Kozo Okazaki, Koichi Kindo, Kazuki Sumida, Shilong Wu, Koji Miyamoto, Taichi Okuda, Hong Ding, G. D. Gu, Tsuyoshi Tamegai, Ronny Thomale, Takuto Kawakami, Masatoshi Sato, Shik Shin. 2018-03-02. Topological Dirac semimetal phase in the iron-based superconductor Fe(Te,Se). https://arxiv.org/abs/1803.00845

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