Magnetic properties of compositionally modulated nitride amorphous alloy films

Abstract

Superstructured Co-based amorphous alloy films comprising non-nitride and nitride layers are prepared by sputtering alternatingly in Ar and in N <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> mixed Ar gas. The layered structure changes into compositionally modulated structure by high temperature annealing above 400°C. The films with modulation wave length λ < 600 Å show appreciable soft magnetic properties. The saturation magnetization, Curie temperature and crystallization temperature increase by nitriding. The obtained compositionally modulated films mainly composed of Co-Nb-N are found to have high saturation magnetization ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4\piM_{s} \approx 10,000</tex> G) as well as high permeability ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\mui \geq 1,000</tex> at 10 MHz) and show high thermal stability even up to 580°C, which was impossible to attain for conventional amorphous films.