Spin-state polaron in lightly hole-doped LaCoO_3

TL;DR

This study reveals that lightly hole-doped LaCoO_3 forms octahedral spin-state polarons involving seven Co ions, explaining the strong magnetic signals observed through various spectroscopic techniques.

Contribution

It provides direct experimental evidence for spin-state polarons in lightly doped LaCoO_3, linking magnetic excitations to polaron formation.

Findings

Observation of intense magnetic excitations with large g-factors

Detection of extended magnetic clusters via NMR

Identification of octahedral spin-state polarons involving seven Co ions

Abstract

Inelastic neutron scattering (INS), electron spin (ESR) and nuclear magnetic resonance (NMR) measurements were employed to establish the origin of the strong magnetic signal in lightly hole-doped La_{1-x}Sr_xCoO_3, x=0.002. Both, INS and ESR low temperature spectra show intense excitations with large effective g-factors ~10-18. NMR data indicate the creation of extended magnetic clusters. From the Q-dependence of the INS magnetic intensity we conclude that the observed anomalies are caused by the formation of octahedrally shaped spin-state polarons comprising seven Co ions.