Microstructural characterisation of electrodeposited Co/Pt multilayers

We have prepared Co/Pt multilayers by electrolysis using a potentiostatic technique. The solution is based on CoSO4.7H2O and K2PtCl6 salts. Our films with periods of (0.8–15) nm have been characterised using X-ray diffraction, electron diffraction analysis of X-rays, scanning electron microscopy and torque magnetometry. Perpendicular magnetic anisotropy was observed for multilayers with Co layers thinner than about 1.0 nm, and a Pt layer thickness of 1.0 nm. A simultaneous multinuclear growth of grains of ordered phases (L10) CoPt or (L12) CoPt3, depending on the electrolysis parameters formed films with very short periodicity. In films with bilayer period thicker than 2.5 nm, polycrystalline h.c.p. Co layers are successive stacked with amorphous Pt layers. Effective magnetic anisotropy per unit volume and coercive field were found to depend on Co layer thickness (tCo) for a series of Co/Pt multilayers with tPt=1 nm and tCo varying in the range (0.3–4) nm.