Tensile-Strain Dependent Spin States in Epitaxial LaCoO$_3$ Thin Films

TL;DR

This study investigates how tensile strain influences the spin states of Co$^{3+}$ ions in LaCoO$_3$ thin films, revealing strain-induced changes in spin configurations using advanced x-ray scattering techniques.

Contribution

It provides direct experimental evidence of strain-dependent spin state transitions in LaCoO$_3$ epitaxial thin films, a topic previously lacking clear experimental validation.

Findings

Tensile strain as small as 1.0% alters spin states.

Resonant inelastic soft x-ray scattering detects spin state ratios.

Strain induces different spin states from bulk LaCoO$_3$.

Abstract

The spin states of Co$^{3+}$ ions in perovskite-type LaCoO$_3$, governed by complex interplay between the electron-lattice interactions and the strong electron correlations, still remain controversial due to the lack of experimental techniques which can detect directly. In this letter, we revealed the tensile-strain dependence of spin states, $i. e.$ the ratio of the high- and low-spin states, in epitaxial thin films and a bulk crystal of LaCoO$_3$ via resonant inelastic soft x-ray scattering. The tensile-strain as small as 1.0% was found to realize different spin states from that in the bulk.