High-field magnetization of URu sub 2 Si sub 2 under high pressure

The temperature dependence of the magnetic susceptibility and the high-field magnetization up to 55 T are measured for URu sub 2 Si sub 2 under high pressures up to 1 GPa. Both T sub chi max and T sub N in the susceptibility increase with increasing pressure. The value of the susceptibility below T sub chi max decreases with increasing pressure. The three high-field metamagnetic transitions at H sub c1 = 35.1 T, H sub c2 = 36.5 T and H sub c3 = 39.6 T at ambient pressure, show different pressure-dependent behaviors. The metamagnetic transition at H sub c1 broadens but survives and its transition field increases with increasing pressure. However, the transition at H sub c2 is smeared out and disappears above 0.4 GPa. The transition at H sub c3 broadens more clearly than the transition at H sub c1 . The fact that both T sub chi max and the metamagnetic transition fields increase suggests that the interaction between the f-electrons and the conduction electrons is enhanced by pressure.