Effect of Pt layer thickness on perpendicular magnetic anisotropy in ultrathin Co/Pt Multilayers

Co/Pt multilayer structures with varying Pt layer thicknesses from 1.5 to 12 Å were deposited on Ta buffer layer by DC magnetron sputtering technique and both of their magnetic and structural properties were investigated. All the multilayers showed perpendicular magnetic anisotropy (PMA) and the enhancement in PMA is observed with increase in the Pt layer thickness. The structural investigation using XRD reveals the presence of single peak in all these multilayers, which indicate the formation of coherent Co/Pt (111) structure. The origin of PMA in these multilayer structure is due to the strain induced in the Co layer. From the full-width-half-maximum (FWHM) of the XRD patterns it is observed that the grain size is increasing with increasing the Pt layer thickness. The influence of the enhancement of the grain size is then correlated with the measured M-H hysteresis behavior and subsequently the anisotropy energy