A full superconducting dome of strong Ising protection in gated monolayer WS2

TL;DR

This study demonstrates a fully tunable superconducting dome in monolayer WS2, showcasing enhanced superconducting properties and resilience to magnetic fields, with insights into re-entrant insulating phases in 2D materials.

Contribution

First demonstration of a complete superconducting dome in gated monolayer WS2, revealing strong Ising protection and re-entrant insulating states in a stable, tunable 2D superconductor.

Findings

Superconductivity achieved in CVD-grown WS2 via gating.

Presence of a full superconducting dome with re-entrant insulating phase.

Strong spin-orbit interaction pins Cooper pair spins, enhancing magnetic resilience.

Abstract

Many recent studies show that superconductivity not only exists in atomically thin monolayers but can exhibit enhanced properties such as higher transition temperature and stronger critical field. Nevertheless, besides being air unstable, weak tunability in these intrinsically metallic monolayers has posed a severe limitation in exploring monolayer superconductivity, hence hindering possible applications in electronic devices. Using field effect gating, we prepared monolayer superconductivity in easily accessible CVD-grown WS2, a typical ambient stable semiconducting transition metal dichalcogenide (TMD). Here, we present a complete set of competitive electronic phases over an unprecedented range from band insulator, superconductor, to an unexpected re-entrant insulator. Throughout the superconducting dome, the Cooper pair spin is pinned by a strong internal spin-orbit interaction, making this material arguably the most resilient superconductor in a magnetic field. The re-entrant insulating state at positive high gating voltages is plausibly attributed to localization induced by the characteristically weak screening of the monolayer, providing the key insight into many dome-like superconducting phases observed in field induced quasi-2D superconductors.