Nature of Defects Induced by Au Implantation in Hexagonal Silicon Carbide Single Crystals
Abstract
We investigate the dynamics of the magnetization reversal in single Pt/Co(0.5 nm)/Pt nano-discs with diameter 130 nm, fabricated by He+ ion irradiation. They exhibit a very narrow distribution of small switching fields and a perpendicular magnetic anisotropy. In spite of their small magnetic volume, thermally activated magnetization reversal cannot be interpreted within the usual Néel-Brown model. Non-coherent magnetization reversal proceeds here by fast nucleation at nano-disc borders and rather slow wall motion towards their center. Dynamics are perfectly accounted for by a 2D-confined droplet model, involving the wall energy rather than the anisotropy energy. On the other hand, the blocking temperature for these nano-discs is well described by the coherent spin reversal model.