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

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(l 10) texture for larger t(FeCoV). The grain size determined from the FeCoV(l 10) 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. (C) 2002 Elsevier Science B.V. All rights reserved.