Fate of Time-Reversal Symmetry Breaking in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>UTe</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>
M. O. Ajeesh, Mitchell M. Bordelon, C Girod, S. Mishra, F. Ronning, E. D. Bauer, B. Maiorov, J. D. Thompson, P. F. S. Rosa, S. M. Thomas
Abstract
Topological superconductivity is a long-sought state of matter in bulk materials, and the odd-parity superconductor UTe<sub>2</sub> is a prime candidate. The recent observation of a field-trainable spontaneous Kerr signal in UTe<sub>2</sub> 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<sub>2</sub> samples—grown via 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<sub>2</sub> 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<sub>2</sub> samples and place strong constraints on the superconducting order parameter of UTe<sub>2</sub>.