Gapped excitations in the high-pressure antiferromagnetic phase of URu2Si2

Abstract

We report a neutron scattering study of the magnetic excitation spectrum in each of the three temperature and pressure driven phases of URu2Si2. We find qualitatively similar excitations throughout the (H0L) scattering plane in the hidden-order and large-moment phases, with no changes in the ω widths of the excitations at the Σ=(1.407,0,0) and Z=(1,0,0) points, within our experimental resolution. There is, however, an increase in the gap at the Σ point from 4.2(2) meV to 5.5(3) meV, consistent with other indicators of enhanced antiferromagnetism under pressure.