Nontrivial superconductivity in topological MoTe2- x S x crystals

Yanan Li; Qiangqiang Gu; Chen Chen; Jun Zhang; Qin Liu; Xiyao Hu; Jun Liu; Yi Liu; Langsheng Ling; Mingliang Tian; Yong Wang; Nitin Samarth; Shiyan Li; Tong Zhang; Ji Feng; Jian Wang

doi:10.1073/pnas.1801650115

Nontrivial superconductivity in topological MoTe_{2- x} S _x crystals

Proc Natl Acad Sci U S A. 2018 Sep 18;115(38):9503-9508. doi: 10.1073/pnas.1801650115. Epub 2018 Aug 30.

Authors

Yanan Li^{1

2

3}, Qiangqiang Gu^{1

2}, Chen Chen^{4

5}, Jun Zhang^{4

5}, Qin Liu^{4

5

6}, Xiyao Hu¹, Jun Liu⁷, Yi Liu^{1

2}, Langsheng Ling⁷, Mingliang Tian⁷, Yong Wang⁸, Nitin Samarth³, Shiyan Li^{4

5

9}, Tong Zhang^{10

5

9}, Ji Feng^{11

2

12}, Jian Wang^{11

2

12}

Affiliations

¹ International Center for Quantum Materials, School of Physics, Peking University, 100871 Beijing, China.
² Collaborative Innovation Center of Quantum Matter, 100871 Beijing, China.
³ Department of Physics, Pennsylvania State University, University Park, PA 16802.
⁴ Department of Physics, State Key Laboratory of Surface Physics, Fudan University, 200433 Shanghai, China.
⁵ Laboratory of Advanced Materials, Fudan University, 200433 Shanghai, China.
⁶ Science and Technology on Surface Physics and Chemistry Laboratory, 621908 Mianyang, China.
⁷ High Magnetic Field Laboratory, Chinese Academy of Sciences, 230031 Hefei, Anhui, China.
⁸ Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Center of Electron Microscopy, Zhejiang University, 310027 Hangzhou, China.
⁹ Collaborative Innovation Center of Advanced Microstructures, 210093 Nanjing, China.
¹⁰ Department of Physics, State Key Laboratory of Surface Physics, Fudan University, 200433 Shanghai, China; tzhang18@fudan.edu.cn jfeng11@pku.edu.cn jianwangphysics@pku.edu.cn.
¹¹ International Center for Quantum Materials, School of Physics, Peking University, 100871 Beijing, China; tzhang18@fudan.edu.cn jfeng11@pku.edu.cn jianwangphysics@pku.edu.cn.
¹² Chinese Academy of Science Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, 100190 Beijing, China.

Abstract

Topological Weyl semimetals (TWSs) with pairs of Weyl points and topologically protected Fermi arc states have broadened the classification of topological phases and provide superior platform for study of topological superconductivity. Here we report the nontrivial superconductivity and topological features of sulfur-doped T_d -phase MoTe₂ with enhanced T_c compared with type-II TWS MoTe₂ It is found that T_d -phase S-doped MoTe₂ (MoTe_2-x S _x , x ∼ 0.2) is a two-band s-wave bulk superconductor (∼0.13 meV and 0.26 meV), where the superconducting behavior can be explained by the s_+- pairing model. Further, measurements of the quasi-particle interference (QPI) patterns and a comparison with band-structure calculations reveal the existence of Fermi arcs in MoTe_2-x S _x More interestingly, a relatively large superconducting gap (∼1.7 meV) is detected by scanning tunneling spectroscopy on the sample surface, showing a hint of topological nontrivial superconductivity based on the pairing of Fermi arc surface states. Our work demonstrates that the T_d -phase MoTe_2-x S _x is not only a promising topological superconductor candidate but also a unique material for study of s_+- superconductivity.

Keywords: Td MoTe2−xSx; Weyl semimetal; s+− superconductivity; topological superconductivity.

Publication types

Research Support, Non-U.S. Gov't