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 $$\hat{b}$$ b ̂ -axis. In applied magnetic fields to at least μ 0 H = 11 T along the $$\hat{c}-{\rm{axis}}$$ c ̂ − axis , the magnetism is found to be field-independent in the (h k0) plane. The scattering intensity is consistent with that expected from U3+/U4+ f-electron spins with preferential orientation along the crystallographic $$\hat{a}$$ a ̂ -axis, and a fluctuating magnetic moment of μ e f f =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.