Thin Metal Films with Dispersion-Hardening Magnetic Layers of Fe–Cr–Co Alloy

Abstract

Purpose. The study of the magnetic properties and surface state of permanent magnet fi lms, not containing precious metals, on a silicon substrate with a magnetization vector in the plane of the fi lm. Methods and methodology. Permanent magnet fi lms are created by magnetron sputtering and subsequent single-stage high-vacuum rapid annealing. The structure of these magnets contains three layers: an adhesive layer of vanadium, a compensation layer of copper, and a ferromagnetic layer of a dispersion-hardening alloy (LDHA) of the Fe-Cr-Co system. The properties of the fi lms were studied using confocal microscopy, X-ray diffractometry. A magnetic hysteresis loop was built using a vibromagnitometer and an assembly for the study of the magneto-optic Kerr effect. The morphology of the surface was studied using an atomic force microscope and a scanning electron microscope. Results. After annealing, a signifi cant bending of the substrates occurred, and with an insuffi cient thickness of the compensation layer, the destruction of both the fi lm and part of the silicon substrate was observed. It was found that the increase in the coercive force of the fi lms correlated with a high level of mechanical stresses in LDHA, characteristic for the decomposition of a supersaturated solid solution of chromium in iron in bulk materials. For the preservation of the permanent magnet fi lm, the thickness of the copper compensation layer must be not less than that of LDHA. Conclusions. For the fi rst time, a permanent magnet fi lm was obtained, based on a layer of dispersion-hardening composition, not containing precious metals, with a level of coercive force suffi cient for use in magnetoresistive integrated magnetic fi eld sensors.

Keywords

• magnetron sputtering
• thin fi lms
• coercive force