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oai:docta.ucm.es:20.500.14352/180602023-08-27T23:27:19Zcom_20.500.14352_14col_20.500.14352_15

Morphological, structural and magnetic evolution of sputtered Fe70Ga30 thin films upon annealing in oxygen atmosphere Bisero, D. Fin, S. Ranchal Sánchez, Rocío 538.9 Sol-gel GaFeO_3 Física de materiales Física del estado sólido 2211 Física del Estado Sólido ©2017 Elsevier B.V. All rights reserved. This work has been financially supported through the project MAT2015-66888-C3-3-R of the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER). We thank “CAI Difracción de rayos-X” of UCM for the X-ray diffractometry measurements, “Centro Nacional de Microscopía” of UCM for EDS measuresuments and Instituto of Sistemas Optoelectrónicos y Microtecnología (ISOM) for using its facilities for the growth and magnetic characterization of the samples. We also want to thank BM25-Spline, the Spanish CRG at ESRF for providing beamtime. We report on the evolution of uncapped Fe_(70)Ga_(30) layers deposited by sputtering and post-growth annealed in oxygen atmosphere in a temperature range from 500 °C to 800 °C. We have investigated the morphology, structure and magnetic properties of films with a thickness of 200 nm deposited on Mo buffer layers on glass substrates. X-ray diffractometry shows a decrease of the lattice parameter up to 600 °C whereas a further increase of the temperature up to 800 °C promotes the transformation to Fe_2O_3. We have observed by x-ray absorption fine structure the partial oxidation of Ga and the formation of Ga aggregates at 600 °C. These aggregates form Ga-rich bubbles that can be observed on the sample surface from which Ga evaporates leaving a Ga-poor layer that is later oxidized into Fe_2O_3. The thermal treatment on oxygen atmosphere has also a clear impact on the magnetic properties of the layers. The uniaxial in-plane magnetic anisotropy of the as-grown film evolves to magnetic isotropy when annealed at 600 °C probably due to the segregation and formation of Ga-rich areas. After Ga evaporates from the sample, Fe is fully oxidized and only a weak ferromagnetism related to Fe_2O_3 is detected. Ministerio de Economía y Competitividad (MINECO)/FEDER Depto. de Física de Materiales Fac. de Ciencias Físicas TRUE pub 2023-06-17T22:05:57Z 2023-06-17T22:05:57Z 2017 journal article https://hdl.handle.net/20.500.14352/18060 0925-8388 10.1016/j.jallcom.2017.04.158 eng MAT2015-66888-C3-3-R open access application/pdf Elsevier Science SA