Anisotropic critical magnetic fluctuations in the ferromagnetic superconductor UCoGe

TL;DR

This study investigates the anisotropic magnetic fluctuations in the ferromagnetic superconductor UCoGe using neutron scattering, revealing unusual damping and anisotropic correlation lengths that may explain its superconducting properties.

Contribution

It provides new insights into the anisotropic critical magnetic excitations and damping in UCoGe, contrasting with related compounds and linking magnetic fluctuations to superconductivity.

Findings

Strong non-Landau damping of magnetic excitations

Significant anisotropy in magnetic correlation length

Compatibility of magnetic parameters with small Fermi surface superconductivity

Abstract

We report neutron scattering measurements of critical magnetic excitations in the weakly ferromagnetic superconductor UCoGe. The strong non-Landau damping of the excitations we observe, although unusual has been found in another related ferromagnet, UGe2 at zero pressure. However, we also find there is a significant anisotropy of the magnetic correlation length in UCoGe that contrasts with an almost isotropic length for UGe2. The values of the magnetic correlation length and damping are found to be compatible with superconductivity on small Fermi surface pockets. The anisotropy may be important to explain why UCoGe is a superconductor at zero pressure while UGe2 is not.