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

authors	Mohseni, F; Baghizadeh, A; Lourenco, AACS; Pereira, MJ; Amaral, VS; Vieira, JM; Amaral, JS
nationality	International
journal	JOM
keywords	ALLOY NANOWIRE ARRAYS; MAGNETIC-PROPERTIES
abstract	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.
publisher	SPRINGER
issn	1047-4838
year published	2017
volume	69
issue	8
beginning page	1427
ending page	1431
digital object identifier (doi)	10.1007/s11837-017-2382-y
web of science category	Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing
subject category	Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing
unique article identifier	WOS:000406021800025