Charge ordering and heavy fermions in the semimetal Yb 4As 3

Abstract

We present a model for Yb 4As 3 which can explain semiquantitatively a number of its unusual properties. Based on the view of the Yb-sites as being aligned on chains, the structural phase transition at T c ⋍ 300 K is described by a band Jahn-Teller effect of correlated electrons being driven by a charge ordering of the Yb-ions. The qualitative behavior of the corresponding elastic constant c 44 is explained. The heavy-fermion behavior on a scale of T ∗ ⋍ 50 K is understood within the framework of a slave-boson approximation to the effective low-temperature Hamiltonian.