The invention is directed to a method of manufacturing a ferromagnetic device (10), having an elongated structure extending along a longitudinal direction (11), comprising a ferromagnetic material, wherein a transverse cross section (20) of the ferromagnetic material, perpendicular to said longitudinal direction, is designed to provide a domain wall velocity above the Walker breakdown limit of the ferromagnetic material. In particular, at least a portion (21-23) of a peripheral contour of the ferromagnetic material forms, in the transverse cross-section (20), a non-orthogonal convex set. For example, the whole peripheral contour may realize a (non-orthogonal) convex polygon.