Local hysteresis variation of Co/Pd nanomultilayers

Local coercivity variation of Co/Pd nanomultilayers has been investigated by measuring the polar Kerr hysteresis loops of the local areas of submicron size using a magneto-optic Kerr microscope system. Interestingly, the local coercivity distribution was very sensitive to an increase in the number of repeats: the (2 Å Co/11 Å Pd)10 sample showed a smooth variation of the local coercivity, while (2 Å Co/11 Å Pd)18 showed a large fluctuation. Based on the thermally activated relaxation model, we have found that this local coercivity variation had a crucial effect on the contrasting magnetization reversal behavior observed in those samples, wall-motion dominant for the former sample and nucleation dominant for the latter one.