Correlated electronic states of Yb4As3 studied with photoemission

By means of high resolution photoemission spectroscopy, clear changes of the Yb 4f spectra with temperature are observed in Yb4As3 The photoemission intensity, which is very low at the Fermi level, decreases as the temperature is lowered in accord with the narrowing of the 4f spectra. The Yb2+ 4f state is stabilized along three [111] long chains and the Yb3+ 4f sate is stabilized along a short [111] chain, resulting from the charge ordering accompanying the structural phase transition. A new model is proposed which describes the changes of electronic states with charge ordering. Studies of Yb-4(As1-xSbx)(3) mixed crystals confirm the present interpretation. (C) 1998 Elsevier Science B.V.