Time-reversal-symmetry Breaking in the Superconducting State of ScS

TL;DR

This study investigates the unconventional superconducting properties of ScS, revealing time-reversal-symmetry breaking and a full gap, suggesting it as a new candidate for unconventional superconductivity.

Contribution

It provides experimental evidence of time-reversal-symmetry breaking in ScS, a novel superconductor with potential unconventional pairing mechanisms.

Findings

Superconducting transition at 5.1 K confirmed by multiple measurements.

Presence of spontaneous magnetic fields indicating time-reversal-symmetry breaking.

Full superconducting gap suggested by specific heat and $ta$SR data.

Abstract

We have studied the electronic properties of ScS, a transition-metal monochalcogenide with rocksalt crystal structure, using magnetization, specific heat, transport, and muon spin rotation/relaxation ($\mu$SR) measurements. All measurements confirm the bulk superconducting in ScS with a transition temperature of $T_{C}$ = 5.1(5) K. Specific heat together with transverse-field $\mu$SR measurements indicate a full gap, while our zero-field $\mu$SR study reveals the presence of spontaneous static or quasi-static magnetic fields emerging when entering the superconducting state. We discuss various possible microscopic origins of the observed time-reversal-symmetry breaking. As none of them can be readily reconciled with a conventional pairing mechanism, this introduces ScS as a novel candidate material for unconventional superconductivity.