Apparent auxetic to non-auxetic crossover driven by Co 2+ redistribution in CoFe 2 O 4 thin films

Ferreiro-Vila, E. ; Iglesias, L. ; Lucas Del Pozo, I. (Universidad de Zaragoza) ; Varela-Dominguez, N. ; Bui, C.T. ; Rivas-Murias, B. ; Vila-Fungueiriño, J.M. ; Jimenez-Cavero, P. (Universidad de Zaragoza) ; Magen, C. (Universidad de Zaragoza) ; Morellon, L. (Universidad de Zaragoza) ; Pardo, V. ; Rivadulla, F.

Resumen: Oxide spinels of general formula AB2O4 (A = Mg2+, Fe2+; B = Al3+, Cr3+, etc.) constitute one of the most abundant crystalline structures in mineralogy. In this structure, cations distribute among octahedral and tetrahedral sites, according to their size and the crystal-field stabilization energy. The cationic arrangement determines the mechanical, magnetic, and transport properties of the spinel and can be influenced by external parameters like temperature, pressure, or epitaxial stress in the case of thin films. Here, we report a progressive change in the sign of the Poisson ratio, ¿, in thin films of CoFe2O4, defining a smooth crossover from auxetic (¿ < 0) to non-auxetic (¿ > 0) behavior in response to epitaxial stress and temperature. Microstructural and magnetization studies, as well as ab initio calculations, demonstrate that such unusual elastic response is actually due to a progressive redistribution of Co2+ among the octahedral and tetrahedral sites of the spinel structure. The results presented in this work clarify a long standing controversy about the magnetic and elastic properties of Co-ferrites and are of general applicability for understanding the stress-relaxation mechanism in complex crystalline structures.

Idioma: Inglés

DOI: 10.1063/1.5087559

Año: 2019

Publicado en: APL Materials 7, 3 (2019), 031109 [6 pp]
ISSN: 2166-532X

Factor impacto JCR: 3.819 (2019)

Categ. JCR: PHYSICS, APPLIED rank: 33 / 154 = 0.214 (2019) - Q1 - T1
Categ. JCR: NANOSCIENCE & NANOTECHNOLOGY rank: 46 / 103 = 0.447 (2019) - Q2 - T2
Categ. JCR: MATERIALS SCIENCE, MULTIDISCIPLINARY rank: 98 / 314 = 0.312 (2019) - Q2 - T1

Factor impacto SCIMAGO: 1.57 - Materials Science (miscellaneous) (Q1) - Engineering (miscellaneous) (Q1)

Financiación: info:eu-repo/grantAgreement/EC/H2020/734187/EU/Spin conversion, logic storage in oxide-based electronics/SPICOLOST
Financiación: info:eu-repo/grantAgreement/ES/MINECO/MAT2016-80762-R
Financiación: info:eu-repo/grantAgreement/ES/MINECO/MAT2017-82970-C2-R

Tipo y forma: Artículo (Versión definitiva)

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