Orbital Ordering and Spin-Ladder Formation in La2RuO5

TL;DR

This study uses electronic structure calculations to analyze the semiconductor transition in La2RuO5, revealing orbital ordering and spin-ladder formation that preserve local magnetic moments, differing from previous theories.

Contribution

It proposes a new orbital ordering scenario in La2RuO5 that explains its magnetic behavior through spin-ladder formation, contrasting with earlier models.

Findings

Orbital ordering preserves local S=1 moments.

Spin-ladders form due to structural changes.

Antiferromagnetic coupling along rungs.

Abstract

The semiconductor-semiconductor transition of La2RuO5 is studied by means of augmented spherical wave (ASW) electronic structure calculations as based on density functional theory and the local density approximation. This transition has lately been reported to lead to orbital ordering and a quenching of the local spin magnetic moment. Our results hint towards an orbital ordering scenario which, markedly different from the previously proposed scheme, preserves the local S = 1 moment at the Ru sites in the low-temperature phase. The unusual magnetic behaviour is interpreted by the formation of spin-ladders, which result from the structural changes occurring at the transition and are characterized by antiferromagnetic coupling along the rungs.