Disorder-Induced Microscopic Magnetic Memory

Abstract

Using coherent x-ray speckle metrology, we have measured the influence of disorder on major loop return point memory (RPM) and complementary point memory (CPM) for a series of perpendicular anisotropy $\mathrm{C}\mathrm{o}/\mathrm{P}\mathrm{t}$ multilayer films. In the low disorder limit, the domain structures show no memory with field cycling---no RPM and no CPM. With increasing disorder, we observe the onset and the saturation of both the RPM and the CPM. These results provide the first direct ensemble-sensitive experimental study of the effects of varying disorder on microscopic magnetic memory and are compared against the predictions of existing theories.