CHARLA: Magnetic-domain-wall AC dynamics in ultrathin ferromagnetic films

DOMENICHINI, P.; PARIS, F.; QUINTEROS, C. P.; GRANADA, M.; GEORGE, J.-M.; CURIALE, J.; BUSTINGORRY, S.; KOLTON, A.B.; CAPELUTO, M. G.; PASQUINI, G.

Bariloche

Workshop; Second International Workshop on Spintronics - Spin Argentina 2022; 2022

The dynamics of domain walls (DWs) under external magnetic fields reveals a complexbehavior where sample disorder plays a key role. Furthermore, the response to alternating (AC)magnetic fields has only been explored in few cases and analyzed in terms of the constant fieldsolution acting on interfaces that are flat on average. Here we present results obtained bymagneto-optical imaging of the evolution of magnetic DWs in ultrathin ferromagnetic filmswith perpendicular anisotropy, under the application of AC magnetic fields within the creepregime. Whereas the DC characterization is well predicted by an elastic flat interface model,unexpected features are observed under the application of alternating square pulses in bubblemicrometer-sized magnetic domains [1]: We show that under a zero bias AC field there is astriking bubble area reduction, concomitant with a DW roughness increase, with furtherevolution to strongly distorted shapes. We propose an analytical model [2], based on thecurvature induced symmetry breaking, which is able to quantitatively explain the intriguing“rectification effect”. Numerical simulations, capable of reproducing the experimentalobservations, support the analytical model. A qualitative explanation of the enhancement oflarge scale dynamic roughening is also proposed.