Field-angular Dependence of Pairing Interaction in URhGe: Comparison with UCoGe

TL;DR

This study investigates how the pairing interactions in URhGe depend on magnetic field orientation, revealing differences from UCoGe that influence their superconducting properties.

Contribution

It provides the first detailed comparison of field-angular dependence of spin fluctuations in URhGe and UCoGe, linking these differences to their superconducting phase diagrams.

Findings

Spin fluctuations in URhGe are robust against magnetic fields below 4 T.

UCoGe's spin fluctuations are suppressed by tiny fields along the c axis.

Differences in spin fluctuation behavior correlate with distinct Hc2 phase diagrams.

Abstract

The field-angular dependence of Co-NMR spin-lattice relaxation rate 1/T1 has been measured for a 10% Co-doped single crystal of URhGe. The experiment revealed that spin fluctuations in ferromagnetic (FM) state of URhGe are robust against magnetic field below about 4 T, applied along any direction in the bc crystal plane. This is in clear contrast with the sister compound UCoGe, in which FM spin fluctuations are rapidly suppressed by a tiny applied field along the c axis. We show that such a difference in the character of the spin fluctuations is reflected in their two distinct phase diagrams for the upper critical field Hc2, providing further support to the mechanism of superconductivity mediated by spin fluctuations in these materials.