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Morphological, structural and magnetic evolution of sputtered Fe70Ga30 thin films upon annealing in oxygen atmosphere

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Bisero, D. and Fin, S. and Ranchal Sánchez, Rocío (2017) Morphological, structural and magnetic evolution of sputtered Fe70Ga30 thin films upon annealing in oxygen atmosphere. Journal of alloys and compounds, 713 . pp. 129-135. ISSN 0925-8388

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Official URL: http://dx.doi.org/10.1016/j.jallcom.2017.04.158


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Abstract

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.


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©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.

Uncontrolled Keywords:Sol-gel; GaFeO_3
Subjects:Sciences > Physics > Materials
Sciences > Physics > Solid state physics
ID Code:44594
Deposited On:06 Oct 2017 14:13
Last Modified:09 Oct 2017 07:57

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