Charge Fluctuations and the Valence Transition in Yb under Pressure

TL;DR

This study uses dynamical mean field theory to investigate the pressure-induced valence transition in Yb, revealing unique charge fluctuation signatures and contrasting it with other lanthanides.

Contribution

It provides the first detailed theoretical analysis of Yb's valence transition under pressure, highlighting its fluctuating valence nature and spectral features.

Findings

Reproduces the volume-dependent valence transition in Yb

Shows transition is accelerated by heating

Identifies unique charge fluctuation signatures

Abstract

We present a dynamical mean field theory study of the valence transition ($f^{14} \to f^{13}$) in elemental, metallic Yb under pressure. Our calculations reproduce the observed valence transition as reflected in the volume dependence of the $4f$ occupation. The transition is accelerated by heating, and suggests quasiparticle or Kondo-like structure in the spectra of the trivalent end state, consistent with the early lanthanides. Results for the local charge fluctuations and susceptibility, however, show novel signatures uniquely associated with the valence transition itself, indicating that Yb is a fluctuating valence material in contrast to the intermediate valence behavior seen in the early trivalent lanthanides Ce, Pr, and Nd.