Interdiffusion Processes in High-Coercivity RF-Sputtered Alnico Thin Films on Si Substrates


Alnico V thin film samples with the thickness of 100 nm were prepared by radio-frequency sputtering on Si substrates with and without a SiO2 layer. Heat treatment of the as-deposited thin films in above ambient pressure in an Ar atmosphere at a temperature range of 600-900A degrees C, followed by quenching and/or slow cooling, leads to higher coercivity values compared to bulk Alnico magnets. Annealing at 800A degrees C followed by quenching results in the highest coercivity reported here of 1.8 kOe. The formation of several triangular-shaped features along the interface between the substrate and the film were observed. A high-resolution transmission electron microscope analysis showed these to be formed via interdiffusion of Fe, Co and Ni atoms into the Si substrate. These features show a large difference in lattice parameters compared with the magnetically soft bulk Fe-Co-Si alloys, and a heterogeneous or layered magnetic ion distribution inside these features could be the origin of the high coercivity observed in the heat-treated films.



subject category

Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing


Mohseni, F; Baghizadeh, A; Lourenco, AACS; Pereira, MJ; Amaral, VS; Vieira, JM; Amaral, JS

our authors


This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement and FCT Project EXPL/CTM-NAN/1614/2013 - FCOMP-01-0124-FEDER-041688. J.S. Amaral would like to acknowledge the financial support of FCT Research Grant IF/01089/2015. A. Baghizadeh acknowledges FCT Project REDE/1509/RME/2005 providing access to electron microscopy facilities in Aveiro University.

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