We present a model which can explain semiquantitatively a number of the unusual properties of \mbox{Yb4As3}. The structural phase transition at Tc≃300\mboxK is described by a band Jahn-Teller effect of correlated electrons and is interpreted as a charge ordering of the Yb ions. The low carrier concentration in the low-temperature phase follows from the strong electron correlations of the 4f-holes on the Yb sites and can be viewed as self-doping of charge-ordered chains. The observed heavy-fermion behaviour is on a scale of T∗≃50\mboxK and is due to spinon-like excitations in the Yb3+-chains. The appearance of a second low-energy scale around 0.2\,K is due to the Fermi energy of the low-density carriers.
@article{arxiv.cond-mat/9504078,
title = {Theoretical Model for the Semimetal Yb_4As_3},
author = {Peter Fulde and Burkhard Schmidt and Peter Thalmeier},
journal= {arXiv preprint arXiv:cond-mat/9504078},
year = {2009}
}