Microscopic return point memory in Co/Pd multilayer films

We have conducted resonant x-ray scattering with a coherent beam on Co/Pd, a system which exhibits perpendicular magnetization. The system forms labyrinth domains and we collect a pure magnetic signal in our transmission geometry. The energy of the incident X-rays is tuned to the Co L$_3$ edge and the coherence is established with a 10 um pinhole. The return and complementary point memory, defined by the correlation between the speckle pattern at whole loops and half-loops respectively, depends on the applied field and is a maximum near initial magnetization reversal, indicating that the system has strong memory during nucleation. As the field is increased, the memory decreases and reaches a minimum as the magnetization begins to saturate. This indicates that the system follows a large path in configuration space as the labyrinths evolve with the applied field.