Atomic-resolution imaging of spin-state superlattices in nanopockets within cobaltite thin films.

Gazquez, Jaume; Luo, Weidong; Oxley, Mark P; Prange, Micah; Torija, Maria A; Sharma, Manish; Leighton, Chris; Pantelides, Sokrates T et al. · Nano Lett · 2011

basic_science · Level V

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Abstract

Certain cobalt oxides are known to exhibit ordered Co spin states, as determined from macroscopic techniques. Here we report real-space atomic-resolution imaging of Co spin-state ordering in nanopockets of La(0.5)Sr(0.5)CoO(3-δ) thin films. Unlike the bulk material, where no Co spin-state ordering is found, thin films present a strain-induced domain structure due to oxygen vacancy ordering, inside of which some nanometer sized domains show high-spin Co ions in the planes containing O vacancies and low-spin Co ions in the stoichiometric planes. First-principles calculations provide support for this interpretation.