Magnetic anisotropy of Co ∕ Cu (111) superlattices: calculation and experiment

The results of theoretical calculations and experimental data for the effective magnetic anisotropy K eff (obtained from ferromagnetic resonance measurements) of [ Co ( 8 Å ) ∕ Cu ( d Cu ) ] 20 ( d Cu = 7 – 22 Å ) superlattices with a coherent interaction of the Co and Cu layers prepared by magnetron sputtering are presented. The experimental values of K eff are an oscillatory function of the thickness d Cu interlayers. The computed and experimentally measured dependences K eff ( d Cu ) are qualitatively similar; stable growth of the parameter K eff with increasing thickness of the nonmagnetic layers is observed (against the background of oscillations of the experimental curve), which is a direct consequence of the growth of axial distortions of the initial cubic structure of cobalt under the conditions of pseudomorphism. The reasons for the appearance of oscillations of K eff are discussed; the main one is the oscillatory behavior of the roughness of the interfaces of the layers with increasing d Cu , resulting in synchronous oscillations of K eff , resistivity, magnetoresistance, and the ferromagnetic resonance linewidth.