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 Angstrom Co/11 Angstrom Pd)(10) sample showed a smooth variation of the local coercivity, while (2 Angstrom Co/11 Angstrom 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. (C) 2000 American Institute of Physics. [S0021-8979(00)89108-2].