Effect of Pd Buffer and Interlayer on the Magnetic Properties of CoCrPt-Oxide Granular Thin Films

Abstract

Morphostructural and magnetic properties of CoCrPt-oxide (TiO2, CoO) granular thin films deposited on Pd( $y$ )/Ru/Pd( $x$ )/NiTa intermediate layer have been investigated as a function of the Pd thickness ( $x = 5$ and 10 nm; $y = 1, 3$ , and 5 nm). The Pd( $x$ ) buffer layer shows an fcc (111) texture that leads to a gradual improvement of both the Ru and CoCrPt hcp (0002) crystallographic orientations while increasing the Pd thickness. This results on a significant enhancement of both the effective magnetic anisotropy ( ${K} _{\mathrm {eff}} =4.1 \times 10^{6}$ erg/cm3) and out-of-plane coercivity ( ${H} _{c\bot } = 5.7$ kOe) with respect to the reference CoCrPt-oxides/Ru/NiTa sample ( $K_{\mathrm {eff}} = 3.4 \times 10^{6}$ erg/cm3, ${H} _{c\bot }= 4.7$ kOe) when a 10 nm-thick Pd buffer is used. The inclusion of a Pd( $y$ ) intermediate layer between Ru and Co leads to an increase of the effective anisotropy (up to $4.1 \times 10^{6}$ erg/cm3 for $y = 5$ nm) with respect to the reference sample, which can be ascribed to a combined effect of an interface contribution and a term arising from a CoCrPt lattice distortion.