Atomic-scale mechanisms for magnetostriction in CoFe2O4 and La0.5Sr0.5CoO3 oxides determined by differential x-ray absorption spectroscopy

Subias, G. (Universidad de Zaragoza) ; Cuartero, V. ; Garcia, J. ; Blasco, J. (Universidad de Zaragoza) ; Pascarelli, S.

Resumen: The atomic environments involved in the magnetostriction effect in CoFe2O4 and La0.5Sr0.5CoO3 poly-crystalline samples have been identified by differential extended x-ray absorption fine structure (DiffEXAFS) spectroscopy. We demonstrate that cobalt atoms at octahedral sites are responsible for their magnetostriction. The analysis of DiffEXAFS data indicates that the local-site magnetostrictive strains of Co atoms are reversed in these two oxides, in agreement with the macroscopic magnetostriction. For the CoFe2O4 spinel, a large negative strain along the (100) direction has been determined for the CoO6 octahedron causing a tetragonal contraction in contrast with the La0.5Sr0.5CoO3 perovskite, where a positive moderate strain along the (100) direction was found resulting in a tetragonal expansion. The different local-site magnetostriction is understood in terms of the different valence and spin state of the Co atoms for the two oxides. The macroscopic magnetostriction would be explained then by the relative change in volume, either contraction in CoFe2O4 or expansion in La0.5Sr0.5CoO3, when the tetragonal axis of the Co site is reoriented under an externally applied magnetic field.

Idioma: Inglés

DOI: 10.1103/PhysRevB.100.104420

Año: 2019

Publicado en: PHYSICAL REVIEW B 100, 10 (2019), 104420 [10 pp]
ISSN: 2469-9950

Factor impacto SCIMAGO: 1.811 - Electronic, Optical and Magnetic Materials (Q1) - Condensed Matter Physics (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E12-R17
Financiación: info:eu-repo/grantAgreement/ES/MICINN-AEI-FEDER/RTI2018-098537-C22

Tipo y forma: Article (Published version)

Área (Departamento): Área Física Materia Condensada (Dpto. Física Materia Condensa.)