Magnetoresistance hysteresis in the superconduting state of Kagome CsV$_3$Sb$_5$

TL;DR

This study reveals unusual hysteretic magnetoresistance behavior in the superconducting state of Kagome CsV$_3$Sb$_5$, suggesting possible chiral superconductivity and time-reversal symmetry breaking.

Contribution

It reports the first observation of hysteresis in magnetoresistance in Kagome superconductor CsV$_3$Sb$_5$, linking it to unconventional superconductivity and chiral order.

Findings

Hysteresis can be induced by large DC or AC currents at low temperatures.

Weak hysteresis observed near the transition temperature with small currents.

Results support the presence of time-reversal-symmetry-breaking superconducting domains.

Abstract

The hysteresis of magnetoresistance observed in superconductors is of great interest due to its potential connection with unconventional superconductivity. In this study, we perform electrical transport measurements on Kagome superconductor CsV$_3$Sb$_5$ nanoflakes and uncover unusual hysteretic behaviour of magnetoresistance in the superconducting state. This hysteresis can be induced by applying either a large DC or AC current at temperatures ($T$) well below the superconducting transition temperature ($T_{\rm c}$). As $T$ approaches $T_{\rm c}$, similar weak hysteresis is also detected by applying a small current. Various scenarios are discussed, with particular focus on the effects of vortex pinning and the presence of time-reversal-symmtery-breaking superconducting domains. Our findings support the latter, hinting at chiral superconductivity in Kagome superconductors.