The magnetic-field-induced valence transition in EuNi2(Si 1-xGex)2 (x = 0.82, 0.85) has been studied by X-ray absorption spectroscopy at low temperatures. The field dependence of the Eu valence is directly observed for the first time. We find a significant decrease in the valences at high magnetic fields above 40 T. The valence of Eu changes from υ* = 2.75 at a zero field to υ* = 2.33 at 40 T for x = 0.82. The results are analyzed using a theoretical model. The hybridization parameter V between the Eu2+ and Eu3+ states and the energy separation ΔE are determined, which are crucial for quantum mechanical mixing.
ASJC Scopus subject areas
- Physics and Astronomy(all)