Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Temperature dependent Eu 3d-4f X-ray Absorption and Resonant
  Photoemission Study of the Valence Transition in $EuNi_2(Si_{0.2}Ge_{0.8})_2$   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.

21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math