Mott transition and suppression of orbital fluctuations in orthorhombic 3$d^{1}$ perovskites

TL;DR

This paper develops a low-energy Hamiltonian for orthorhombic 3d1 perovskites, incorporating electronic correlations with a new DMFT approach, revealing how correlations and distortions suppress orbital fluctuations and induce insulating behavior.

Contribution

It introduces a novel implementation of dynamical mean-field theory for non-cubic systems and applies it to explain the Mott transition in orthorhombic 3d1 perovskites.

Findings

Correlation effects suppress orbital fluctuations in LaTiO3 and YTiO3.

The interplay of correlations and distortions favors the insulating state.

Good agreement with photoemission data confirms the model's validity.

Abstract

Using $t_{2g}$ Wannier-functions, a low-energy Hamiltonian is derived for orthorhombic $3d^{1}$ transition-metal oxides. Electronic correlations are treated with a new implementation of dynamical mean-field theory for non-cubic systems. Good agreement with photoemission data is obtained. The interplay of correlation effects and cation covalency (GdFeO$_{3}$-type distortions) is found to suppress orbital fluctuations in LaTiO$_{3},$ and even more in YTiO$_{3}$, and to favor the transition to the insulating state.