Intermediate Valence State in $\mathrm{Yb}{\mathrm{B}}_4$ Revealed by Resonant X-ray Emission Spectroscopy

Abstract

We report the temperature dependence of the Yb valence in the geometrically frustrated compound $\mathrm{Yb}{\mathrm{B}}_4$ from 12 to 300 K using resonant X-ray emission spectroscopy at the Yb $L_{{\alpha }_1}$ transition. We find that the Yb valence, $v$, is hybridized between the $v=2$ and $v=3$ valence states, increasing from $v=2.61\pm 0.01$ at 12 K to $v=2.67\pm 0.01$ at 300 K, confirming that $\mathrm{Yb}{\mathrm{B}}_4$ is a Kondo system in the intermediate valence regime. This result indicates that the Kondo interaction in $\mathrm{Yb}{\mathrm{B}}_4$ is substantial, and is likely to be the reason why $\mathrm{Yb}{\mathrm{B}}_4$ does not order magnetically at low temperature, rather than this being an effect of geometric frustration. Furthermore, the zero-point valence of the system is extracted from our data and compared with other Kondo lattice systems. The zero-point valence seems to be weakly dependent on the Kondo temperature scale, but not on the valence change temperature scale $T_v$.

References in corpus (1)

• Quantum Criticality in Heavy Fermion Metals

Cited by in corpus (2)

• Topological Mixed Valence Model in Magic-Angle Twisted Bilayer Graphene
• Anomalous pressure dependence of the bulk modulus and Yb valence in cubic YbPd