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 tTi=1.04 nm and tFeCoV=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 tFeCoV. The grain size determined from the FeCoV(1 1 0) peaks displays a decreasing trend with decreasing tFeCoV indicating that the grain size is mainly determined by the tFeCoV. 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 Ks=0.826 mJ/m2 and Kv=-1.84 MJ/m3, respectively. The data analysis indicates that the samples may have their easy direction of magnetization perpendicular to the film plane for tFeCoV<0.89 nm.The saturation magnetization is observed to decrease with decreasing tFeCoV and from a plot of MstFeCoV vs. tFeCoV we have determined a dead layer thickness of 0.33 nm at the FeCoV interfaces. The variation of coercivity and remanence with tFeCoV may be due to both random anisotropy and superparamagnetism. The decrease in remanence with decreasing tFeCoV can also be attributed to the progressive change of the easy direction of magnetization away from the film plane