Nano-magnetic droplets and implications to orbital ordering in La1-xSrxCoO3

TL;DR

This study reveals how nano-magnetic droplets and orbital ordering influence magnetic interactions in La1-xSrxCoO3, showing a transition from dynamic to static ferromagnetic correlations with doping and metallicity.

Contribution

It provides new insights into the role of orbital ordering and nano-magnetic droplets in the magnetic properties of doped cobalt oxides.

Findings

Identification of a 0.6 meV low energy excitation linked to orbital ordering.

Observation of static ferromagnetic droplets increasing with doping.

Correlation length and temperature of droplets grow with metallicity.

Abstract

Inelastic cold neutron scattering on LaCoO3 provided evidence for a distinct low energy excitation at 0.6 meV coincident with the thermally induced magnetic transition. Coexisting strong ferromagnetic (FM) and weaker antiferromagnetic (AFM) correlations that are dynamic follow the activation to the excited state, identified as the intermediate S=1 spin triplet. This is indicative of dynamical orbital ordering favoring the observed magnetic interactions. With hole doping as in La1-xSrxCoO3, the FM correlations between Co spins become static and isotropically distributed due to the formation of FM droplets. The correlation length and condensation temperature of these droplets increase rapidly with metallicity due to the double exchange mechanism.