Coexistence of Intrinsic Superconductivity and Topological Insulator State in Monoclinic Phase WS2

TL;DR

This paper reports the discovery of intrinsic superconductivity and topological insulator states in monoclinic WS2, highlighting its potential as a new topological superconductor with high transition temperature and anisotropic electronic properties.

Contribution

The study reveals monoclinic WS2 as a new material exhibiting both superconductivity and topological insulator states without external tuning.

Findings

Superconducting transition temperature of 8.8 K in monoclinic WS2

Presence of a topological insulator state with a single Dirac cone

Strong electronic anisotropy observed in the material

Abstract

Recently, intriguing phenomena of superconductivity, type-II Weyl semimetal or quantum spin Hall states were discovered in metastable 1T'-type VIB-group transition metal dichalcogenides (TMDs). Here, we report that monoclinic phase WS2 was discovered and synthesized in our experiments. The intrinsic superconducting transition was observed in monoclinic WS2 with a transition temperature Tc of 8.8 K which is the highest among previously reported TMDs without any fine-tuning process. Intersteing, topological insulator state, defined by topological invariant Z2, was also discovered with a single Dirac cone on the surface, which is different from all topological states reported in TMDs. Further, the electronic structure was found to have a strong anisotropy by Shubnikov-de Haas oscillations and first-principles calculations. Our findings reveal that monoclinic WS2 might be a new topological superconductivity candidate with a strong anisotropy.