Temperature dependent Eu 3d-4f X-ray Absorption and Resonant Photoemission Study of the Valence Transition in $EuN{i}_2(S{i}_{0.2}G{e}_{0.8}{)}_2$

Abstract

We study the mixed valence transition ($T$${}_v$ $\sim$80 K) in EuNi${}_2$(Si${}_{0.2}$Ge${}_{0.8}$)${}_2$ using Eu 3$d-4f$ X-ray absorption spectroscopy (XAS) and resonant photoemission spectroscopy (RESPES). The Eu${}^{2+}$ and Eu${}^{3+}$ main peaks show a giant resonance and the spectral features match very well with atomic multiplet calculations. The spectra show dramatic temperature ($T$)-dependent changes over large energies ($\sim$10 eV) in RESPES and XAS. The observed non-integral mean valencies of $\sim$2.35 $\pm$ 0.03 ($T$ = 120 K) and $\sim$2.70 $\pm$ 0.03 ($T$ = 40 K) indicate homogeneous mixed valence above and below $T$${}_v$. The redistribution between Eu${}^{2+}$$4f^7$+$[spd{]}^0$ and Eu${}^{3+}$$4f^6$+$[spd{]}^1$ states is attributed to a hybridization change coupled to a Kondo-like volume collapse.

arXiv comment4 pages, 3 figures

References in corpus (3)

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• The alpha to gamma transition in Ce: a theoretical view from optical spectroscopy
• Auger Effect in the High-Resolution Ce 3d-edge Resonant Photoemission

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