Anisotropic magnetic field dependence of the magnetization dynamics in UPd2Al3

The magnetization dynamics of the magnetic superconductor UPd2Al3 has been investigated by inelastic neutron scattering in the normal and superconducting, antiferromagnetically ordered state under a magnetic field applied parallel to the hexagonal c axis. Within the available resolution, the dynamic response below 2.5 meV is insensitive to the applied field on the scale of the field dependence reported by E. Blackburn [Phys. Rev. B 74, 024406 (2006)] in which the field was applied in the basal plane. Our results support that the previously reported field dependent quasielastic contribution is related to the dynamics of the rotation of the magnetic moment. The changes observed in the inelastic part of the excitation spectrum are consistent with those expected from spin-wave theory. Interestingly, the anisotropic field dependence of the normal-state response may be correlated with the superconducting properties of this material.