Spin-orbital locked magnetic excitations in a half-metallic double perovskite Ba2FeReO6

TL;DR

This study investigates magnetic excitations in Ba2FeReO6, revealing two dispersing modes and highlighting the role of spin-orbit coupling in its magnetic behavior, thus positioning double perovskites as key systems for exploring correlated spin-orbit phenomena.

Contribution

It introduces a local moment model that explains magnetic excitations in Ba2FeReO6 by incorporating spin-orbit locked moments on Re, advancing understanding of 5d transition metal oxides.

Findings

Identification of two magnetic modes in Ba2FeReO6

Development of a model capturing spin-orbit interactions

Implication of double perovskites for studying correlated spin-orbit effects

Abstract

We present a powder inelastic neutron scattering study of magnetic excitations in Ba$_2$FeReO$_6$, a member of the double perovskite family of materials which exhibit half-metallic behavior and high Curie temperatures. We find clear evidence of two well-defined dispersing magnetic modes in its low temperature ferrimagnetic state. We develop a local moment model, which incorporates the interaction of Fe spins with spin-orbit locked magnetic moments on Re, and show that this captures our experimental observations. Our study further opens up double perovskites as model systems to explore the interplay of strong correlations and spin-orbit coupling in 5d transition metal oxides.