Magnetic field dependence of DW roughness in Pt/Co/Pt films

JORDAN, D.; CURIALE, J.; QUINTEROS, C.; GRANADA, M.; CORTES BURGOS, M. J.; BUSTINGORRY, S.

San Carlos de Bariloche

Workshop; Yielding phenomena in disordered systems, the southernmost STATPHYS27 satellite; 2019

In ferromagnetic materials, under certain conditions, magnetic domains with magnetizations pointing in different directions may coexist. The transition regions between those domains are known as domain walls (DWs). In thin ferromagnetic films, the DWs can be treated as one-dimensional elastic objects that move in a two-dimensional disordered medium by thermally activated processes under the application of an external magnetic field. The competition between elastic energy, disorder, temperature and the external driving force gives rise to the DW roughness. This roughness is quantified by studying how the spatial fluctuations in the DW position increase with the system size, and it contains non-trivial geometric properties of the DWs [1]. Taking into account that the geometric parameters of the DWs (roughness exponent and amplitude) are linked to the dynamical properties, and that such properties are of interest not only from the fundamental point of view but also by the potential impact in the development of devices, understanding the relationship between the geometric and dynamic properties is a subject of great relevance and current interest [2-4].In this work, using polar magneto-optic microscopy, we address the study of magnetic domain wall roughness and dynamics in ultrathin Pt/Co/Pt films with perpendicular anisotropy [4,5]. We focus in the creep regime, where the DW velocity varies exponentially with the applied magnetic field, and we study the evolution of the roughness exponent and amplitude with the DW velocity.ReferencesBarab ́asi, A. L. & Stanley, H. E., (1995) Fractal Concepts in Surface Growth, Cambridge Univ. Press.S. Bustingorry et al. Phys. Rev. B 85, 214416 (2012). E. E. Ferrero et al. Phys. Rev. E 87, 032122 (2013).