Connection between f-electron correlations and magnetic excitations in UTe2

TL;DR

This study uses inelastic neutron scattering to explore the anisotropic magnetic excitations in UTe2, revealing their origin from f-electron hybridization and their behavior under magnetic fields, contributing to understanding its superconducting properties.

Contribution

It provides detailed insights into the anisotropic magnetic excitations and their relation to f-electron correlations in UTe2, a candidate spin-triplet superconductor.

Findings

Magnetic excitations originate from the Brillouin zone boundary at Y and T points.

Magnetism remains field-independent up to 11 T along the c-axis.

Excitations are consistent with U3+/U4+ f-electron spins with a fluctuating moment of 2.3 μB.

Abstract

The detailed anisotropy of the low-temperature, low-energy magnetic excitations of the candidate spin-triplet superconductor UTe$_2$ is revealed using inelastic neutron scattering. The magnetic excitations emerge from the Brillouin zone boundary at the high symmetry $Y$ and $T$ points and disperse along the crystallographic $\hat{b}$-axis. In applied magnetic fields to at least $\mu_0 H=11$~T along the $\hat{c}-$axis, the magnetism is found to be field-independent in the $(hk0)$ plane. The scattering intensity is consistent with that expected from U$^{3+}$/U$^{4+}$ $f$-electron spins with preferential orientation along the crystallographic $\hat{a}$-axis, and a fluctuating magnetic moment of 2.3(7) $\mu_B$. These characteristics indicate that the excitations are due to intraband spin excitons arising from $f$-electron hybridization.