Field-induced valence transition of EuNi2(Si1−xGex)2 in ultra-high magnetic fields

Abstract The EuNi 2 (Si 1− x Ge x ) 2 system exhibits a temperature- and field-induced valence transition from Eu 3+ to Eu 2+ in the concentration range 0.75⩽ x ⩽0.85. In this study, we performed magnetization measurements on compounds with 0.5⩽ x ⩽0.75 in ultra-high fields up to 300 T generated by explosive compression of magnetic flux. We observed a jump of the magnetization, indicating a field-induced valence change from Eu 3+ to Eu 2+ for each compound. The critical field increases linearly with decreasing x and reaches a value of 225 T for x =0.5.