In order to investigate the nature of the trivalent state induced by pressure, we have examined the magnetization of EuNi2(Ge1-xSix)2 with x = 0.15 under high pressure up to 1.2GPa in pulsed magnetic fields up to 40T 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.
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