Doping-driven Mott transition in La_{1-x}Sr_xTiO_3 via simultaneous electron and hole doping of t2g subbands

TL;DR

This study investigates the insulator-metal transition in La_{1-x}Sr_xTiO_3, revealing how simultaneous electron and hole doping of t2g subbands induces a first-order transition with phase separation and large subband compressibilities.

Contribution

It demonstrates that weak hole doping causes significant interorbital charge transfer and phase separation, providing new insights into doping effects in multi-band Mott insulators.

Findings

Weak hole doping triggers large interorbital charge transfer.

The transition is first-order with phase separation.

Subband compressibilities become very large and opposite in sign.

Abstract

The insulator to metal transition in LaTiO_3 induced by La substitution via Sr is studied within multi-band exact diagonalization dynamical mean field theory at finite temperatures. It is shown that weak hole doping triggers a large interorbital charge transfer, with simultaneous electron and hole doping of t2g subbands. The transition is first-order and exhibits phase separation between insulator and metal. In the metallic phase, subband compressibilities become very large and have opposite signs. Electron doping gives rise to an interorbital charge flow in the same direction as hole doping. These results can be understood in terms of a strong orbital depolarization.