paper

The fate of time-reversal symmetry breaking in UTe2

arXiv:2305.00589 · doi:10.1103/PhysRevX.13.041019

Abstract

Topological superconductivity is a long-sought state of matter in bulk materials, and odd-parity superconductor UTe $_{2}$ is a prime candidate. The recent observation of a field-trainable spontaneous Kerr signal in UTe $_{2}$ at the onset of superconductivity provides strong evidence that the superconducting order parameter is multicomponent and breaks time-reversal symmetry. Here, we perform Kerr effect measurements on a number of UTe $_{2}$ samples -- grown $v ia$ both chemical vapor transport and the molten-salt-flux methods -- that show a single superconducting transition between 1.6~K and 2.1~K. Our results show no evidence for a spontaneous Kerr signal in zero field measurements. This implies that the superconducting state of UTe $_{2}$ does not intrinsically break time-reversal symmetry. Instead, we observe a field-trainable signal that varies in magnitude between samples and between different locations on a single sample, which is a sign of inhomogeneous magnetic regions. Our results provide an examination of representative UTe $_{2}$ samples and place strong constraints on the superconducting order parameter of UTe $_{2}$ .