Field-induced magnetic anisotropy in La0.7Sr0.3CoO3

TL;DR

This study investigates the magnetic anisotropy in La0.7Sr0.3CoO3, revealing a high anisotropy linked to a spin-state transition of Co ions under magnetic fields, which affects the material's magnetic properties.

Contribution

It provides new insights into the magnetic anisotropy of La0.7Sr0.3CoO3 and proposes a spin-state transition as the cause of anomalous anisotropy behavior.

Findings

Magnetic anisotropy is significantly higher than in manganites.

Discrepancy between anisotropy from saturation magnetization and coercive fields.

Spin-state transition of Co ions enhances orbital angular momentum and anisotropy.

Abstract

Magnetic anisotropy has been measured for the ferromagnetic La0.7Sr0.3CoO3 perovskite from an analysis of the high-field part of the magnetization vs. field curves, i.e., the magnetic saturation regime. These measurements give a magnetic anistropy one order of magnitude higher than that of reference manganites. Surprisingly, the values of the magnetic anisotropy calculated in this way do not coincide with those estimated from measurements of coercive fields which are one order of magnitude smaller. It is proposed that the reason of this anomalous behaviour is a transition of the trivalent Co ions under the external magnetic field from a low-spin to an intermediate-spin state. Such a transition converts the Co3+ ions into Jahn-Teller ions having an only partially quenched orbital angular momentum, which enhances the intra-atomic spin-orbit coupling and magnetic anisotropy.