Evidence for triplet superconductivity near an antiferromagnetic instability in CrAs

TL;DR

This study investigates the superconducting state in CrAs near an antiferromagnetic instability, revealing evidence for an unconventional odd-parity spin triplet pairing through angular dependence measurements of the upper critical field.

Contribution

The paper provides experimental evidence for triplet superconductivity in CrAs, highlighting its unconventional nature near an antiferromagnetic quantum critical point.

Findings

Six maxima in the upper critical field with six-fold and two-fold symmetry.

Evidence suggests an odd-parity spin triplet pairing state.

Superconductivity emerges as helimagnetic order is suppressed by pressure.

Abstract

Superconductivity was recently observed in CrAs as the helimagnetic order is suppressed by applying pressure, suggesting possible unconventional superconductivity. To reveal the nature of the superconducting order parameter of CrAs, here we report the angular dependence of the upper critical field under pressure. Upon rotating the field by 360 degrees in the $bc$-plane, six maxima are observed in the upper critical field, where the oscillations have both six-fold and two-fold symmetric components. Our analysis suggests the presence of an unconventional odd-parity spin triplet state.