Jahn-TellerAnB4−nresonance polaron model for amorphous metals

Abstract

Jahn-Teller polaron resonances localized on ${A}_{n}{B}_{4\ensuremath{-}n}$ clusters provide a microscopic basis for two-level tunneling centers and for nonmagnetic Kondo anomalies in amorphous metals. The most active tunneling centers belong to a mixed-valence regime, while in a different regime, the model gives a pseudospin Kondo Hamiltonian with a cutoff $\ensuremath{\sim}{\ensuremath{\omega}}_{D}$. The virtual-state model is used to obtain analytic expressions for the adiabatic polaron potentials.