Seminário com o Prof. Dr. Rafael Leonardo Novak- 08 de julho de 2015 – 16 horas

06/07/2015 14:10

 O PROGRAMA DE PÓS-GRADUAÇÃO EM FÍSICA convida para o seminário: 

Domain growth and dipolar bias in magnetic thin films coupled to aperiodic pinning potential

Prof. Dr. Rafael Leonardo Novak

UFSC / Campus Blumenau

 Resumo:

Domain walls are playing an increasingly important role in new, experimental data storage technologies, as they can be easily manipulated by current and/or magnetic and electric fields. Controllable pinning is paramount for these applications and extrinsic, non-traditional sources of domain wall pinning, such as spatially varying dipolar fields and focused ion beam irradiation, have been proposed as means of tailoring magnetization reversal and domain wall pinning over short length scales. Here we detail magneto-optical studies of domain wall motion and domain wall mediated switching in a continuous, magnetically soft, ultrathin [Pt/Co]x (x = 1 or 2) film with perpendicular anisotropy which is coupled to an array of harder [Co/Pt]4 magnetic nanodots via dipolar interaction across a thin Pt spacer. In the absence of nanodots, the domain wall dynamics is dominated by thermally activated creep, while the stray field underneath the nanodot array gives rise to a spatially periodic pinning potential for domain walls propagating through the underlying continuous film which leads to field-asymmetric reversal and exchange-bias-like phenomena. We observe strikingly different domain wall morphologies depending on the field polarity and the strength of the coupling between the nanodots and the underlying layer, as well as domain wall velocity differences of up to 3 orders of magnitude and transitions from compact faceted to percolation-like dendritic domain wall propagation modes. We show that the average domain wall mobility of a magnetic thin film can be controlled by an external parameter, in this casethe magnetization state of an array of magnetic nanodots, opening the possibility of controlling domain wall propagation paths in thin magnetic films.

 

Data: 08 de julho de 2015 – (quarta-feira) – Local: Sala 212 – Auditório do Departamento de Física – Horário: 16 horas

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