Oxygen stoichiometry, crystal structure, and magnetism in La$_{0.5}$Sr$_{0.5}$CoO$_{3-\delta}$

TL;DR

This study investigates how oxygen deficiency affects the crystal structure and magnetic properties of La$_{0.5}$Sr$_{0.5}$CoO$_{3-elta}$, revealing that increased oxygen vacancies weaken ferromagnetism and alter magnetic transition behavior.

Contribution

It provides a comprehensive analysis of oxygen stoichiometry's impact on structure and magnetism, combining experimental characterization with first-principles calculations.

Findings

Oxygen vacancies reduce saturation magnetization at 5 K.

Samples with higher elta show broader magnetic transitions.

First-principles calculations elucidate the effect of oxygen non-stoichiometry on ferromagnetic ordering.

Abstract

We have prepared a series of polycrystalline samples La$_{0.5}$Sr$_{0.5}$CoO$_{3-\delta}$} with $0 < \delta \le 0.21$ and characterized their oxygen content, crystal structure, and magnetic properties. While the fully oxygenated samples are good ferromagnets, samples with larger $\delta$ values display increasingly broad magnetic transitions. The saturation magnetization at 5 K falls rapidly as $\delta$ increases. First principles electronic structure calculations provide insights into the magnetic behavior of the fully oxygenated compound, and the manner in which ferromagnetic ordering is affected by increasing oxygen non-stoichiometry.