Stabilization of charge ordering in La_(1/3)Sr_(2/3)FeO_(3-d) by magnetic exchange

TL;DR

This study investigates how magnetic exchange interactions stabilize charge ordering in La_(1/3)Sr_(2/3)FeO_(3-d), revealing that magnetic effects can drive charge order independently of Coulomb interactions.

Contribution

The paper provides experimental evidence that magnetic exchange energies can stabilize charge ordering in doped iron oxides, highlighting a magnetic mechanism distinct from Coulomb-driven models.

Findings

Magnetic exchange ratios support charge ordering driven by magnetic interactions.

Doped holes are delocalized, reducing antiferromagnetic exchange.

Charge ordering occurs without Coulomb interaction dominance.

Abstract

The magnetic exchange energies in charge ordered La_(1/3)Sr_(2/3)FeO_(3-d) (LSFO) and its parent compound LaFeO_(3) (LFO) have been determined by inelastic neutron scattering. In LSFO, the measured ratio of ferromagnetic exchange between Fe3+ - Fe5+ pairs (J_F) and antiferromagnetic exchange between Fe3+ - Fe3+ pairs (J_AF) fulfills the criterion for charge ordering driven by magnetic interactions (|J_F/J_AF| > 1). The 30% reduction of J_AF as compared to LFO indicates that doped holes are delocalized, and charge ordering occurs without a dominant influence from Coulomb interactions.