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

TL;DR

This study explores how hole doping induces orbital disorder and metal-insulator transitions in perovskite vanadium oxides, revealing the effects of doping level and disorder on electronic phases.

Contribution

It provides detailed phase diagrams showing the relationship between hole doping, orbital order melting, and MIT in vanadium oxides with different electron correlation strengths.

Findings

Orbital order melts before or with the MIT as doping increases.

Y_{1-x}Ca_xVO_3 loses orbital order immediately at x=0.02.

Critical doping for MIT depends on the parent compound's electron correlation.

Abstract

Filling-control metal-insulator transitions (MITs) and related electronic phase diagrams have been investigated for hole-doped vanadium oxides, Pr_{1-x}Ca_xVO_3, Nd_{1-x}Sr_xVO_3 and Y_{1-x}Ca_xVO_3, 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 ramdom potential arising from the quenched disorder. In particular, the G-type spin- and C-type orbital-ordered phase present in Y_{1-x}Ca_xVO_3 disappears immediately upon hole doping, around x=0.02. On the other hand, the critical doping level x for MIT is governed by the electron-correlation strength of the undoped parent compound.