Direct Observation of the Topological Surface State in the Topological Superconductor 2M-WS2

Soohyun Cho; Soonsang Huh; Yuqiang Fang; Chenqiang Hua; Hua Bai; Zhicheng Jiang; Zhengtai Liu; Jishan Liu; Zhenhua Chen; Yuto Fukushima; Ayumi Harasawa; Kaishu Kawaguchi; Shik Shin; Takeshi Kondo; Yunhao Lu; Gang Mu; Fuqiang Huang; Dawei Shen

doi:10.1021/acs.nanolett.2c02372

Direct Observation of the Topological Surface State in the Topological Superconductor 2M-WS₂

Nano Lett. 2022 Nov 23;22(22):8827-8834. doi: 10.1021/acs.nanolett.2c02372. Epub 2022 Nov 11.

Authors

Soohyun Cho^{1

2}, Soonsang Huh³, Yuqiang Fang^{4

5}, Chenqiang Hua⁶, Hua Bai⁶, Zhicheng Jiang¹, Zhengtai Liu^{1

2}, Jishan Liu^{1

2}, Zhenhua Chen⁷, Yuto Fukushima³, Ayumi Harasawa³, Kaishu Kawaguchi³, Shik Shin³, Takeshi Kondo^{8

3}, Yunhao Lu⁶, Gang Mu¹, Fuqiang Huang^{4

5}, Dawei Shen^{1

2}

Affiliations

¹ State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai200050, People's Republic of China.
² Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing100049, People's Republic of China.
³ Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba277-8581, Japan.
⁴ State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai200050, People's Republic of China.
⁵ State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing100871, People's Republic of China.
⁶ Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou310027, People's Republic of China.
⁷ Shanghai Synchrotron Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, People's Republic of China.
⁸ Trans-Scale Quantum Science Institute, The University of Tokyo, Bunkyo-ku, Tokyo113-0033, Japan.

PMID: 36367457
DOI: 10.1021/acs.nanolett.2c02372

Abstract

The quantum spin Hall (QSH) effect has attracted extensive research interest because of the potential applications in spintronics and quantum computing, which is attributable to two conducting edge channels with opposite spin polarization and the quantized electronic conductance of 2e²/h. Recently, 2M-WS₂, a new stable phase of transition metal dichalcogenides with a 2M structure showing a layer configuration identical to that of the monolayer 1T' TMDs, was suggested to be a QSH insulator as well as a superconductor with a critical transition temperature of around 8 K. Here, high-resolution angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES are applied to investigate the electronic and spin structure of the topological surface states (TSS) in the superconducting 2M-WS₂. The TSS exhibit characteristic spin-momentum-locking behavior, suggesting the existence of long-sought nontrivial $Z_{2}$ topological states therein. We expect that 2M-WS₂ with coexisting superconductivity and TSS might host the promising Majorana bound states.

Keywords: 2M-WS2; ARPES; monolayer 1T′ TMDs; spin-resolved ARPES; superconductor; topological surface state.