Observation of Topological Superconductivity in a Stoichiometric Transition Metal Dichalcogenide 2M-WS2

TL;DR

This study reports the discovery of topological superconductivity in the naturally occurring 2M-WS2, a stoichiometric transition metal dichalcogenide, showing topological surface states with a nodeless superconducting gap, promising for quantum computing applications.

Contribution

It provides the first evidence of intrinsic topological superconductivity in a stoichiometric TMD without complex tuning or heterostructures.

Findings

Observation of topological surface states in 2M-WS2

Superconducting gap on TSSs is nodeless and similar to bulk gap

2M-WS2 is an intrinsic topological superconductor

Abstract

Topological superconductors (TSCs) are unconventional superconductors with bulk superconducting gap and in-gap Majorana states on the boundary that may be used as topological qubits for quantum computation. Despite their importance in both fundamental research and applications, natural TSCs are very rare. Here, combining state of the art synchrotron and laser-based angle-resolved photoemission spectroscopy, we investigated a stoichiometric transition metal dichalcogenide (TMD), 2M-WS2 with a superconducting transition temperature of 8.8 K (the highest among all TMDs in the natural form up to date) and observed distinctive topological surface states (TSSs). Furthermore, in the superconducting state, we found that the TSSs acquired a nodeless superconducting gap with similar magnitude as that of the bulk states. These discoveries not only evidence 2M-WS2 as an intrinsic TSC without the need of sensitive composition tuning or sophisticated heterostructures fabrication, but also provide an ideal platform for device applications thanks to its van der Waals layered structure.