Magnetic edge fields in UTe$_2$ near zero background fields

TL;DR

This study investigates magnetic edge fields in UTe$_2$, a potential chiral superconductor, revealing edge magnetic signals consistent with chiral order but lacking domain evidence, highlighting challenges in confirming chiral superconductivity.

Contribution

The paper provides experimental evidence of magnetic edge fields in UTe$_2$ and discusses the complexities in identifying chiral superconductivity due to hidden magnetic sources.

Findings

Detected magnetic fields at UTe$_2$ edges consistent with chiral order

Did not observe expected chiral domains in the samples

Results suggest hidden magnetism complicates chiral superconductor identification

Abstract

Chiral superconductors are theorized to exhibit spontaneous edge currents. Here, we found magnetic fields at the edges of UTe$_2$, a candidate odd-parity chiral superconductor, that seem to agree with predictions for a chiral order parameter. However, we did not detect the chiral domains that would be expected, and recent polar Kerr and muon spin relaxation data in nominally clean samples argue against chiral superconductivity. Our results show that hidden sources of magnetism must be carefully ruled out when using spontaneous edge currents to identify chiral superconductivity.