We study the mixed valence transition (Tv∼80K) in EuNi2(Si0.2Ge0.8)2 using Eu 3d-4f x-ray absorption spectroscopy (XAS) and resonant photoemission spectroscopy (RESPES). The Eu2+ and Eu3+ main peaks show a giant resonance and the spectral features match very well with atomic multiplet calculations. The spectra show dramatic temperature (T) dependent changes over large energies (∼10eV) in RESPES and XAS. The observed nonintegral mean valencies of ∼2.35±0.03(T=120K) and ∼2.70±0.03(T=40K) indicate homogeneous mixed valence above and below Tv. The redistribution between Eu2+4f7+[spd]0 and Eu3+4f6+[spd]1 states is attributed to a hybridization change coupled to a Kondo-like volume collapse.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||出版済み - 10 15 2005|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics