Magnetic Anisotropy of Ni Films Prepared by Ion Beam Sputtering

Abstract

The magnetic anisotropy in Ni films deposited by ion beam sputtering (IBS), triode rf sputtering and diode rf sputtering, was studied in relation to the internal stress in the films. A strong in-plane easy-axis magnetic anisotropy (K u ? -5 × 105 erg/cm3) was observed in IBS Ni films deposited at room temperature under an accelerating voltage exceeding 1 kV. The internal compressive stress was found to be as large as -1.2 × 1010 dyn/cm2, which caused a stress-induced magnetic anisotropy of about -1.2 × 106 erg/cm3 in the IBS Ni films. There is some positive contribution to the magnetic anisotropy, possibly due to the anisotropic internal shape effect (K int ? = 6 × 105 erg/cm3). Both this perpendicular magnetic anisotropy and the stress-induced in-plane anisotropy decreased with increasing substrate temperature during deposition. It is possible to obtain a stress-free, isotropic IBS Ni film at an appropriate substrate temperature (250 to 300°C) and at an appropriate ion beam accelerating voltage (1.1 kV).