NMR Study of In-Plane Twofold Ordering in URu2Si2

We report Si-29 NMR spectra and Knight shift measurements as a function of applied field orientation in the (001) basal plane of URu2Si2. Observed linewidth oscillations confirm the in-plane twofold ordered domain state observed in recent magnetic susceptibility measurements. Analysis of our linewidth data leads to estimate similar to 0.4% for the twofold intrinsic (monodomain) susceptibility anisotropy in the basal plane, a value similar to 15 times smaller than that obtained from recent susceptibility measurements.