Chirality-Induced Asymmetric Magnetic Nucleation inPt/Co/AlOxUltrathin Microstructures

Abstract

The nucleation of reversed magnetic domains in $\mathrm{Pt}/\mathrm{Co}/{\mathrm{AlO}}_x$ microstructures with perpendicular anisotropy was studied experimentally in the presence of an in-plane magnetic field. For large enough in-plane field, nucleation was observed preferentially at an edge of the sample normal to this field. The position at which nucleation takes place was observed to depend in a chiral way on the initial magnetization and applied field directions. A quantitative explanation of these results is proposed, based on the existence of a sizable Dzyaloshinskii-Moriya interaction in this sample. Another consequence of this interaction is that the energy of domain walls can become negative for in-plane fields smaller than the effective anisotropy field.