Eu 4d-4f resonant photoemission and optical reflectivity measurements of a temperature- induced valence transition material, EuNi2(Si0.25Ge 0.75)2, have been performed at several temperatures. The valence transition was observed and the mean valence was evaluated to be 2.37 ± 0.02 and 2.75 ± 0.25 below and above the valence transition temperature, respectively. The mixing between the Ni 3d conduction band and the Eu3+ 4/ hole becomes weak as the temperature increases, showing the valence transition from Eu3+ to Eu2+.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)