X-Ray Absorption Study of Mixed-Valence TmSe

Abstract

The ${L}_{\mathrm{III}}$ x-ray absorption edge of Tm in TmSe yields a temperature-independent valence of 2.58\ifmmode\pm\else\textpm\fi{}0.07. The thermal damping of the extended x-ray absorption fine structure of TmSe is nearly identical to that of ErSe. This indicates very weak coupling of breathing shell charge fluctuations of the Tm ions to the phonons and very little static disorder of the lattice.