A STUDY OF MAGNETISATION REVERSAL MECHANISMS IN Co/Pt MULTILAYERS.

Abstract

In this paper we report on the preparation of sputter deposited Co/Pt multilayer thin films and the study of magnetisation reversal mechanisms in these films which are potential magneto-optic media. We have examined these mechanisms using well established bulk magnetic measurement techniques. Reverse domain nucleation and domain wall pinning controlled materials have been identified. We relate reversal mechanisms, including a bimodal process, to the hysteresis loops in terms of a two coercivity model. We have analysed the reversal processes using irreversible susceptibility curves obtained from measurements of remanence curves, and ΔM curves that reveal the effects of interaction mechanisms on reversal. We observe that close to saturation the samples exhibit weakly positive values of ΔM that indicate that the magnetised state is supported even though only domain wall processes are present. We also report experimental values obtained for coercivity, saturation fields, reverse domain nucleation and reverse domain wall critical fields. We explain deviations between values of the domain wall critical field obtained from isothermal remanent magnetisation and DC demagnetisation measurements in terms of the width of the domain wall energy barrier distribution. We identify a correlation between the values for these fields, and hence the reversal mechanisms exhibited by particular samples, and the structure of the films.