Electronic and Magnetic Properties of $\rm{RMnO}_3/\rm{AMnO}_3$ Heterostructures

TL;DR

This study models the electronic and magnetic behaviors of RMO/AMO heterostructures, revealing interface states similar to bulk compounds, and discovering exotic intermediate magnetic states not seen in bulk phase diagrams.

Contribution

It introduces a two-orbital double-exchange model to analyze heterostructures, identifying interface states and novel intermediate magnetic phases.

Findings

Interface states resemble bulk (R,A)MO at 0.5 electron density.

Depending on bandwidth, states are charge/orbital ordered or A-AF.

Discovery of exotic intermediate magnetic states.

Abstract

In this paper, we investigate the ground state properties of the $\rm{RMnO}_3/\rm{AMnO}_3$ ($\rm{RMO/AMO}$) heterostructures (R=trivalent cation, and A=divalent cation) by using a two-orbital double-exchange model supplemented by the Poisson's equation. We find that the state stabilized near the interface of the heterostructure is similar to the state of the bulk compound $\rm{(R,A)MO}$ at electronic density close to 0.5. Depending on the bandwidth it will be a charge and orbital ordered CE state or an A-AF state with $x^2-y^2$ orbital order. Our results can explain some properties of long-period superlattices. As another interesting result, we find exotic intermediate states stabilized in between the interface and the bulk-like regimes of the heterostructure. For instance, a spin "canted CE" state and others. They may not have an analog in experimentally known bulk phase diagrams, but provide a natural interpolation between magnetically-ordered states that are stable in the bulk at different electronic densities.