A survey of anisotropy measurement techniques and study of thickness effect on interfacial and volume anisotropies in Co/Pt multilayer media

A survey of various measurement techniques, including the rotation method, the hard-axis hysteresis loop, and the torque measurement, is presented using Co/Pt multilayer recording media. It is found that for highly exchange-coupled samples, the results from the rotational method are consistent with those from the hard-axis hysteresis loop and torque measurements. Such anisotropy measurements are applied to determine the interfacial anisotropy in Co/Pt multilayers (MLs) by studying a series of Co/Pt ML samples with Co thickness ranging from 0.1 to 2 nm. The Pt thickness is fixed at either 1 or 0.5 nm. It is found that the multilayer with 1 nm Pt layer shows a larger interfacial anisotropy constant (K-S similar to 0.8 erg/cm(2)) than the media with 0.5 nm Pt layer (K-S similar to 0.6 erg/cm(2)), corresponding to about 80% and 60% of the interfacial anisotropy of the ML made by molecular-beam epitaxy, respectively [D. Weller , Mater. Res. Soc. Symp. Proc. 313, 791 (1993)]. Such thickness dependence is supported by the x-ray-diffraction superlattice peak measurements that indicate the discontinuous growth for the case with thinner Pt. (C) 2006 American Institute of Physics.