79005 20230330095433.0 doi 10.1063/1.5087559 sideral 111479 ART-2019-111479 eng Ferreiro-Vila, E. Apparent auxetic to non-auxetic crossover driven by Co 2+ redistribution in CoFe 2 O 4 thin films 2019 Access copy available to the general public Unrestricted 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. info:eu-repo/grantAgreement/EC/H2020/734187/EU/Spin conversion, logic storage in oxide-based electronics/SPICOLOST This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 734187-SPICOLOST info:eu-repo/grantAgreement/ES/MINECO/MAT2016-80762-R info:eu-repo/grantAgreement/ES/MINECO/MAT2017-82970-C2-R info:eu-repo/semantics/openAccess by http://creativecommons.org/licenses/by/3.0/es/ 3.819 2019 PHYSICS, APPLIED 33 / 154 = 0.214 2019 Q1 T1 NANOSCIENCE & NANOTECHNOLOGY 46 / 103 = 0.447 2019 Q2 T2 MATERIALS SCIENCE, MULTIDISCIPLINARY 98 / 314 = 0.312 2019 Q2 T1 1.57 2019 Materials Science (miscellaneous) 2019 Q1 Engineering (miscellaneous) 2019 Q1 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Iglesias, L. Lucas Del Pozo, I. Universidad de Zaragoza (orcid)0000-0003-0271-8713 Varela-Dominguez, N. Bui, C.T. Rivas-Murias, B. Vila-Fungueiriño, J.M. Jimenez-Cavero, P. Universidad de Zaragoza (orcid)0000-0003-0400-8600 Magen, C. Universidad de Zaragoza (orcid)0000-0002-6761-6171 Morellon, L. Universidad de Zaragoza (orcid)0000-0003-3724-508X Pardo, V. Rivadulla, F. 2003 395 Universidad de Zaragoza Dpto. Física Materia Condensa. Área Física Materia Condensada 7, 3 (2019), 031109 [6 pp] APL mater. APL Materials 2166-532X 934657 http://zaguan.unizar.es/record/79005/files/texto_completo.pdf Versión publicada 103237 http://zaguan.unizar.es/record/79005/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:79005 articulos driver 2023-03-30-09:42:00 ARTICLE