Transient magnetic domain wall AC dynamics by means of MOKE microscopy

Abstract

The domain wall response under constant external magnetic fields reveals a complex behavior where sample disorder plays a key role. Furthermore, the response to alternating magnetic fields has only been explored in limited cases and analyzed in terms of the constant field solution. Here we unveil phenomena in the evolution of magnetic domain walls under the application of alternating magnetic fields within the creep regime, well beyond a small fuctuation limit of the domain wall position. Magnetic field pulses were applied in ultra-thin ferromagnetic films with perpendicular anisotropy, and the resulting domain wall evolution was characterized by polar magneto-optical Kerr effect microscopy. Whereas the DC characterization is well predicted by the elastic interface model, striking unexpected features are observed under the application of alternating square pulses: magneto-optical images show that after a transient number of cycles, domain walls evolve toward strongly distorted shapes concomitantly with a modification of domain area. The morphology of domain walls is characterized with a roughness exponent when possible and contrasted with alternative observables which result to be more suitable for the characterization of this transient evolution. The final stationary convergence as well as the underlying physics is discussed.

9 pages, 8 figures

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Cited by in corpus (7)

• A numerical study of the statistics of roughness parameters for fluctuating interfaces
• Domain-wall roughness in GdFeCo thin films: crossover length scales and roughness exponents
• Degradation of domains with sequential field application
• Curvature-driven AC-assisted creep dynamics of magnetic domain walls
• Effect of Ir growth pressure on the domain wall dynamics in Ta/Pt/Co/Ir/Ta stacks
• Microscopic interplay of temperature and disorder of a one-dimensional elastic interface
• Field-dependent roughness of moving domain walls in a Pt/Co/Pt magnetic thin film