Pressure-induced metal-insulator transition in LaMnO3 is not of Mott-Hubbard type

TL;DR

This study shows that the pressure-induced metal-insulator transition in LaMnO3 is driven by orbital splitting rather than Mott-Hubbard physics, requiring Coulomb interactions and Jahn-Teller distortion for insulating behavior.

Contribution

It demonstrates that the transition in LaMnO3 under pressure is caused by orbital effects, challenging the traditional Mott-Hubbard transition explanation.

Findings

Transition at 32 GPa is due to orbital splitting, not Mott-Hubbard physics.

Both Coulomb repulsion and Jahn-Teller distortion are necessary for insulating state.

The transition mechanism is different from classic Mott-Hubbard models.

Abstract

Calculations employing the local density approximation combined with static and dynamical mean-field theories (LDA+U and LDA+DMFT) indicate that the metal-insulator transition observed at 32 GPa in paramagnetic LaMnO3 at room temperature is not a Mott-Hubbard transition, but is caused by orbital splitting of the majority-spin eg bands. For LaMnO3 to be insulating at pressures below 32 GPa, both on-site Coulomb repulsion and Jahn-Teller distortion are needed.