Steplike versus continuous domain propagation in Co/Pd multilayer films

We investigate the microscopic reversal behavior in perpendicular-anisotropy magnetic thin films using an integrated mask-sample design that allows probing a nanoscale sample region with soft x-rays. Local hysteresis loops and spectroholography images are obtained from the transmitted signal exploiting x-ray magnetic circular dichroism. Our data provide direct evidence of microscopic spin-flip avalanches, such as responsible for Barkhausen noise. In comparison with macroscopic magnetometry measurements we find evidence for the sputter pressure dependent introduction of local defects that prevent a continuous domain wall motion but are not strong enough to introduce the appearance of microscopic return point memory.