Influences of film microstructure and defects on magnetization reversal in bit patterned Co/Pt multilayer thin film media

Abstract

Quasisingle crystalline and polycrystalline Co/Pt multilayered films were prepared via sputtering technique. The polycrystalline Co/Pt multilayers exhibited an appreciable number of planar defects such as twin boundaries and stacking faults whereas few defects were present for the quasisingle crystalline films. The polycrystalline films had smoother surface, and as patterned into arrays of small islands, a smaller critical size for single domain was unexpectedly observed. The corresponding magnetic domain images revealed that nucleation interestingly occurred at any locations of a patterned element, which was attributed to the observed defects. Moreover, micromagnetic modeling was utilized to further quantitatively study influences of an anisotropically soft region (which can represent existing defects) in the patterned element on nucleation field in terms of exchange coupling strength.