Perpendicular magnetic anisotropy, hysteresis and structural properties of nanostructured FeCoV/Ti multilayers

Abstract

FeCoV/Ti multilayers are investigated in order to study perpendicular magnetic anisotropy, variation of saturation magnetization, remanence, coercivity and structural properties. Five samples with t Ti =1.04 nm and t FeCoV =0.89–4.47 nm are prepared by DC magnetron sputtering. X-ray diffraction measurements carried out on the samples show a strong FeCoV(1 1 0) texture for larger t FeCoV. The grain size determined from the FeCoV(1 1 0) peaks displays a decreasing trend with decreasing t FeCoV indicating that the grain size is mainly determined by the t FeCoV. We have performed magnetic hysteresis measurements in order to investigate various magnetic properties. The interface/surface and volume anisotropy constants determined from the measurements are K s =0.826 mJ/m 2 and K v =−1.84 MJ/m 3 , respectively. The data analysis indicates that the samples may have their easy direction of magnetization perpendicular to the film plane for t FeCoV <0.89 nm .The saturation magnetization is observed to decrease with decreasing t FeCoV and from a plot of M s t FeCoV vs. t FeCoV we have determined a dead layer thickness of 0.33 nm at the FeCoV interfaces. The variation of coercivity and remanence with t FeCoV may be due to both random anisotropy and superparamagnetism. The decrease in remanence with decreasing t FeCoV can also be attributed to the progressive change of the easy direction of magnetization away from the film plane.