INTERACTION FIELDS AND MEDIA NOISE IN COPTCR THIN-FILMS

Remanence measurements have been made on a series of CoPtCr thin films of varying composition in order to correlate the interaction field wi th media noise. delta M versus h curves have been analyzed using a phe nomenological model of Che and Bertram, in which the interaction field is given by h(int) = alpha M(R) + beta(1-M(R)(2)), where M(R) = M(r) (or M(d)). We have shown analytically that alpha and beta can be simpl y determined respectively from the area under the delta M versus h cur ve (or delta h versur M(R)) and the zero crossing of the curve. The pa rameter beta, which is related to the strength of the fluctuation fiel d, was found to increase with increasing reverse de erase noise (measu red at zero remanence). Surprisingly, perhaps, no correlation was foun d between this noise and alpha. By contrast, alpha, which characterize s the strength of the magnetostatic and/or exchange interaction, was p ositive for all samples and decreased with increasing de erase noise ( measured at saturation remanence). As expected, alpha was also found t o increase with the magnetic viscosity, S, and to decrease as the coer civity, H-c, increased.