Field-induced magnetic anisotropy in

$\chem{La_{0.7}Sr_{0.3}CoO_3}$

Author： Mira J. Rivas J. Vázquez M. Ibarra M. R. Caciuffo R. Señarís Rodríguez M. A.

E-ISSN： 1286-4854|62|3|433-438

ISSN： 0295-5075

Source： EPL (EUROPHYSICS LETTERS), Vol.62, Iss.3, 2010-03, pp. : 433-438

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Abstract

Magnetic anisotropy has been measured for the ferromagnetic$\chem{La_{0.7}Sr_{0.3}CoO_3}$ perovskite from an analysis of thehigh-field part of the magnetization vs. field curves,i.e., the magnetic saturation regime. These measurements give amagnetic anistropy one order of magnitude higher than that ofreference manganites. Surprisingly, the values of the magneticanisotropy calculated in this way do not coincide with thoseestimated from measurements of coercive fields which are oneorder of magnitude smaller. It is proposed that the reason ofthis anomalous behaviour is a transition of the trivalent Co ionsunder the external magnetic field from a low-spin to anintermediate-spin state. Such a transition converts the$\chem{Co^{3+}}$ ions into Jahn-Teller ions having an onlypartially quenched orbital angular momentum, which enhances theintra-atomic spin-orbit coupling and magnetic anisotropy.