Variation of the magnetic domain structure with reversal field (invited)

A rate dependence of the magnetic domain structure has been observed in a Pt/Co multilayer. The form of the domain structure as a function of the rate of change of magnetization was studied using nanosecond pulsed magnetic fields. At low fields the magnetization pattern consists of a dendritic like growth of the domains. As the magnitude of the pulse field is increased the patterns change to a more circular structure with smooth boundaries. The change in structure can be quantified and is discussed in terms of a field dependence where different behaviors can be clearly identified. The structure observed results from a narrowing of the distribution of energy barriers to reversal as the field is increased.