Anisotropy of magnetic susceptibility of URu2Si2 under pressure

We have carried out measurements of magnetic susceptibility on a single crystal of the heavy fermion compound URu2Si2 under pressure up to 0.7 GPa. The external magnetic fields were applied parallel to a- and c-axes. Hidden order transition at T-0 and first-order phase transition between hidden ordered phase and large-staggered-moment antiferromagnetic phase at T-M are observable in both measurements. Temperature dependence of magnetic susceptibility of a- and c-axes exhibits a kink and a drop at T-0 and T-M, respectively. However, the magnitude of the variation on a-axis at T-0 and T-M were about one tenth of those on c-axis, respectively. We conclude that the HO phase has a similar anisotropy to that of AFM phase.