Synchrotron X-ray and magnetic measurements were made of a set of five CoCrPt thin films; each sputter-deposited onto CrV underlayers after successively increasing the base

pressure to which the system was evacuated before charging with Ar. It was found that an increase in the residual N gas in the chamber promoted the formation of face-centered cubic-like regions in the mainly hexagonal close-packed Co-alloy grains, by increasing the stacking-fault density. The type and probability of stacking faults were determined from X-ray data, and were found to increase with increasing base pressure: varying from 9 to 30% for samples grown at 10-8 and 10-4Torr, respectively. These stacking faults caused an increase in regions of low coercivity; thus promoting thermally-activated magnetization reversal. The irreversible magnetization reversal processes and interactions were examined in detail by using remanence, ΔM and magnetic viscosity measurements. The ΔM measurements provided a measure of the intergranular interactions. Significant differences were observed in the switching field distributions and ΔM curves. A large increase in activation volume was also observed for films with over 20% of stacking faults. It was proposed that this was due to a reduction in the anisotropy fields caused by the crystallographic defects; which then allowed exchange coupling to dominate the reversal and cause cooperative reversal. The degree of in- and out-of-plane c-axis texture in the films was also investigated and it was found that this also depended upon the level of N contamination, as the c-axis texture was very poor in films grown under the worst vacuum conditions. In the case of the other films, evidence was found for some degree of circumferential c-axis texture in the plane of the sample.

Crystallographic Defects in CoCrPt Thin Film Media - Effect on Interactions and Magnetic Viscosity. H.Laidler, L.Holloway, K.O’Grady: Journal of Physics D, 2002, 35[6], 512-9