A study of the effect of process-parameters on the magnetic anisotropy of cobalt-based soft amorphous thin films.

摘要

This research is concerned with investigating the magnetic and structural properties resulting from various sputtering conditions and post-deposition treatments, and with evaluating the influence of processing-parameters on the magnetic anisotropies in Co-based, soft amorphous thin films deposited by sequential RF co-sputtering.; The magnetic properties and morphological structures of these films were studied as a function of deposition parameters. In TEM the morphology of the film structure consisted of small, electron-dense areas surrounded by a matrix of lower electron density. Experimental anomalies in the magnetizations and Curie temperatures, and an extended range of compositions over which the amorphous phase was stable, indicated that the electron dense regions were Co-rich.; The effects of thermal and magnetic field annealing on the magnetic softness and the permeability of the amorphous thin films were investigated as a function of processing parameters. Rotating field annealing (RFA) was found to be more effective than simple thermal annealing in reducing the Hc and Hk (by factors of {dollar}approx{dollar}10) and enhancing {dollar}musb{lcub}rm i{rcub}{dollar} ({dollar}approx{dollar}3 times larger). An anomalous high frequency permeability response was observed for the films with anneal-induced, ultra-soft, magnetic properties. This response is incompatible with that of the coherent spin rotation initially expected.; We also studied the changes in the nanoscale morphologies of these films produced by thermal and rotating magnetic field annealing. These observations appear to indicate that the major residual source of anisotropy in these sputtered films is atomic scale; e.g. pair ordering.; Room temperature, magnetic after-effects were measured for films made under different processing conditions. Assuming first order log (t) kinetics, the thermal activation energies of these films were determined from the measured temperature dependence of, the resistivity decay in RFA and of, the induced anisotropy change.; Possible origins of the induced magnetic anisotropy and, mechanisms for their formation, consistent with the experimental observations of this work are discussed. Using the results of the study, films with anisotropies less than 0.02 oersteds and state-of-the-art permeabilities were processed. (Abstract shortened with permission of author.)