Field-induced valence transition under high pressure in EuNi2(Ge1−xSix)2

Abstract In order to investigate the nature of the trivalent state induced by pressure, we have examined the magnetization of EuNi 2 (Ge 1− x Si x ) 2 with x =0.15 under high pressure up to 1.2 GPa in pulsed magnetic fields up to 40 T at 4.2 K. The compound shows a field-induced valence transition at 0.2–0.5 GPa. This valence transition is of first order, accompanied with a large hysteresis. A proportional relation between the transition field and temperature is observed.