A scenario for the electronic state in the manganase perovskites: the orbital correlated metal

TL;DR

This paper proposes that manganase perovskites exhibit a correlated metallic state influenced by orbital degrees of freedom near a metal-insulator transition, modeled through a two-band Hubbard approach and quantum Monte Carlo simulations.

Contribution

It introduces a novel scenario where orbital correlations dominate in manganase perovskites, modeled via a simplified single-band approach derived from a two-band Hubbard model.

Findings

Model captures orbital effects in manganase perovskites.

Quantum Monte Carlo results support the correlated metallic state.

Scenario explains experimental observations in transition metal oxides.

Abstract

We argue that, at low temperatures and well into the ferromagnetic phase, the physics of the manganase perovskites may be characterized by a correlated metallic state near a metal insulator transition where the orbital degrees of freedom play a main role. This follows from the observation that a two-band degenerate Hubbard model under a strong magnetic field can be mapped onto a para-orbital single band model. We solve the model numerically using the quantum Monte Carlo technique within a dynamical mean field theory which is exact in the limit of large lattice connectivity. We argue that the proposed scenario may allow for the qualitative interpretation of a variety of experiments which were also observed in other (early) transition metal oxides.