Orbital disordering and the metal-insulator transition with hole doping in perovskite-type vanadium oxides

Abstract

Filling-control metal-insulator transitions (MITs) and related electronic phase diagrams have been investigated for hole-doped vanadium oxides Pr1-x Cax V O3, Nd1-x Srx V O3, and Y1-x Cax V O3 with perovskite structure. The increase of the doping level x causes the melting of the G -type (and C -type) orbital order, prior to or concomitantly with the MIT, due partly to the doped-hole motion and partly to the random potential arising from the quenched disorder. In particular, the G -type spin- and C -type orbital-ordered phase present in Y1-x Cax V O3 disappears immediately upon hole doping, around x=0.02. On the other hand, the critical doping level x for the MIT is governed by the electron-correlation strength of the undoped parent compound. © 2005 The American Physical Society.