Double exchange model in cubic vanadates

TL;DR

This paper explores how the double exchange mechanism stabilizes the metallic C-type antiferromagnetic phase in hole-doped La$_{1-x}$Sr$_x$VO$_3$, highlighting the role of orbital-specific hopping and electron interactions.

Contribution

It introduces a model combining double exchange, Hund's coupling, and Coulomb repulsion to explain the stability of the C-AF phase in cubic vanadates.

Findings

C-AF and metallic phases can be stabilized by specific hopping features.

Double exchange mechanism is crucial for phase stability.

Slave boson method reveals the interplay of interactions and orbital degeneracy.

Abstract

We investigate the role of the double exchange mechanism for stability of the metallic C-type antiferromagnetic (C-AF) phase, which was observed experimentally in hole doped La$_{1-x}$Sr$_x$VO$_3$. The double exchange model treats localized electrons in xy orbitals as classical S=1/2 spins, which interact by Hund's exchange $J_H$ with yz/zx electrons in partly filled $t_{2g}$ orbitals. Including strong on-site Coulomb repulsion $U$ between $t_{2g}$ electrons, and using slave boson method we demonstrate that C-AF and metallic phase can be stabilized due to the specific features of the hopping in degenerate and partly filled $t_{2g}$ orbitals.