Connection between f-electron correlations and magnetic excitations in UTe2

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 $\hat{I}{¼}_{0}H=11$~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) $\hat{I}{¼}_B$. These characteristics indicate that the excitations are due to intraband spin excitons arising from $f$-electron hybridization.

10 pages, 5 figures; Fixed typos