Tunable magnetic anisotropy in obliquely sputtered Co60Fe40 thin films on Si(100)

Abstract

Effect of substrate rotation on the structural, magneto-optic and magneto-transport properties of DC magnetron sputtered Co60Fe40 thin films is investigated. Two thin film samples (each of 20 nm thickness) were prepared by rotating (S-WR) and without rotating (S-WOR) the substrate during deposition. X-ray diffraction (XRD) patterns reveal that the films exhibit textured crystallographic orientation. Surface morphological analysis of these films indicate that the surface of S-WR is smooth in comparison to the sample S-WOR. The magneto-optic Kerr effect analysis reveals that the sample S-WR is isotropic in nature whereas a large uniaxial anisotropy is present in the sample S-WOR due to textured orientation as supported by XRD study. The effect of rotation on the anisotropy is further demonstrated by measuring magneto-resistance (MR) in two configurations, i.e., longitudinal (LMR) and transverse magnetoresistance (TMR) configurations. In the sample S-WOR, the values of MR are quite different, i.e., 0.29% (TMR) and −0.10% (LMR) whereas identical MR values, i.e., 0.19% (for both LMR and TMR), were observed in the sample S-WR. This indicates that the anisotropy in CoFe can be suppressed by rotating the substrates during growth. Thus the tunability of anisotropy is possible by rotating the substrate which is potentially useful for manipulating the properties of ferromagnetic materials for spintronic applications.