Effects of substrate bias on magnetocrystalline anisotropy Ku of CoPt thin films with increasing Pt content

The magnetocrystalline anisotropy Ku of continuous Co1−xPtx alloy films peaks at 30 at. % of Pt. Further increase in Pt at. % decreases Ku quickly probably due to the increasing density of stacking faults SFs and the fcc phases. The effect of substrate bias has been studied in various compositions of CoPt films. Ku increases from 8 10 6 to 1.1 107 ergs /cm3 when 50 V bias was applied to Co60Pt40 films and decreases with further increase in bias. Pt at. % slightly increases from 40 to 43 at. %, which is opposed to the initial Ku increase. However, the SF density and the fcc content are greatly reduced in the biased samples. The transmission electron microscopy images of the biased films show less faulted atomic planes in the hcp CoPt grains. Such improvement in structural defects helps increase Ku in magnetic thin films. © 2009 American Institute of Physics. DOI: 10.1063/1.3067558