Magnetic and structural characterization and ferromagnetic resonance study of thin film HITPERM soft magnetic materials for data storage applications

Abstract

HITPERM/SiO 2 single and multilayer thin films have been produced using a target composition of (Fe70Co30)88Zr7B4Cu1. The as-deposited HITPERM film contains small bcc (or B2) nanocrystals of volume fraction less than 10% surrounded by an amorphous matrix. The lattice parameter of the nanocrystal is about 5% larger than an equilibrium FeCo phase. The saturation induction determined from FMR measurements (1.53±0.08 T) is consistent with VSM and SQUID measurements (1.45–1.5 T) and also with as-spun amorphous ribbons (1.55–1.62 T). The Landé g-factors (2.15±0.05) are typical of transition metals, particularly, of Fe. The Landau–Lifshitz–Gilbert damping parameters of the single and multilayered films are small (α = 0.0055±0.0004) with each layer acting almost independently. Neither thickness variation of each layer nor the number of stacking significantly affects the damping process in a range of film thicknesses of 50–150 nm, while the coercivities are strongly dependent on those parameters. This supports a notion that the damping parameter is an intrinsic property.