Magnetic properties of amorphous Fe-Si-B films prepared by Co-sputtering

Abstract

Amorphous Fe-Si-B films have been fabricated by rf tetrode co-sputtering from a composite target, which was a pure iron plate covered by chips of pure silicon and boron. SEM and EPMA studies showed that there had been neither apparent columnar texture nor compositional fluctuation in the specimen films. The typical values of saturation magnetization per gram σs, initial permeability μi, and coercive force Hc at room temperature were approximately 160 emu/g, 850, and 5 Oe, respectively. The value of μi increased remarkably with increasing the annealing temperature below the crystallization temperature (∼470 °C), while no appreciable change of σs by the annealing was detected. The annealing at about 450 °C raised μi up to approximately 3000. The as-sputtered films had a comparatively large anisotropy with easy axis perpendicular to the film plane, but the stress removal by the annealing at the temperature above 370 °C decreased Hc down to 0.6 Oe. The saturation magnetostriction λs was ∼30×10−6.