SmB6: A material with anomalous energy distribution function of charge carriers?

Abstract

We argue that because of valence-fluctuation caused dynamical changes (fluctuations) of impurity energies in an impurity band of valence fluctuating semiconductors both occupied and unoccupied sites can be found in the impurity band above as well as below the Fermi level even in the ground state. As a consequence, the ground state energy distribution function of the subsystem of localized charge carriers for valence fluctuating semiconductors is qualitatively different than one for conventional semiconductors at T = 0 K, what sheds new light on interpretation of experimental results of valence fluctuating semiconductors, e.g. SmB6 and YbB12, at lowest temperatures.