Surface and Microstructure Analysis of CoCrPt Film on RuCoCrX (X = Ti, Re) Intermediate Layers

Abstract

The microstructural and magnetic properties of perpendicular anisotropic CoCrPt films deposited on Ru or RuCoCrX (X = Ti, Re) intermediate layers were studied. The c-axis of CoCrPt grains were promoted by (0002) textured RuCoCr, and RuCoCrX (X = Ti, Re) intermediate layers due to smaller lattice misfit as compared to Ru. The narrower rocking width (Δθ50 = 3.76°) in RuCoCrRe intermediate layer and CoCrPt shows higher out of plane coercivity (Hc = 6.2 kOe), magnetic anisotropy constant (Ku = 6.2 × 106 erg/cm3) and nucleation field (HN = −2.8kOe) as compared to the Ru intermediate layer (Hc = 5.4 kOe, Ku = 5.9 × 106 erg/cm3, HN = −1.6 kOe). The partial intergranular exchange decoupling of CoCrPt grains was observed. The grain boundaries oxides were formed by the residual oxygen in targets and sputtering processes. The minor Cr2O3, CoO, TiO2, ReO3 oxides were investigated by surface analysis. Due to the minor oxides and Cr segregation at grains boundaries, the CoCrPt films present high coercivity. Samples CoCrPt/RuCoCr and CoCrPt/RuCoCrTi present a minimum at 45° but the values are much higher than the ideal Stoner-Wohlfarth theoretical value 0.5 which could be due to fewer natural oxides for magnetic grains separation. In sample CoCrPt/RuCoCrRe, there is an increase of intergranular interaction as indicated by the large asymmetry and the shift of the minimum at lower angles.