Connection between f-electron correlations and magnetic excitations in UTe2

Abstract

The detailed anisotropic dispersion of the low-temperature, low-energy magnetic excitations of the candidate spin-triplet superconductor UTe₂ 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 μ₀H = 11 T along the \(\hat{c}-{\rm{axis}}\), the magnetism is found to be field-independent in the (hk0) plane. The scattering intensity is consistent with that expected from U³⁺/U⁴⁺ f-electron spins with preferential orientation along the crystallographic \(\hat{a}\)-axis, and a fluctuating magnetic moment of μ_eff=1.7(5) μ_B. We propose interband spin excitons arising from f-electron hybridization as a possible origin of the magnetic excitations in UTe₂.