Oscillatory Reduction of Domain Wall Depinning Field by Transverse Magnetic Field in Ferromagnetic Permalloy Nanowires

Reported herein is a possible way of controlling the depinning field of magnetic domain walls (DWs) by using a magnetic field H _T transverse to the nanowire. A typical notch structure—in the form of triangles on both edges of ferromagnetic Permalloy nanowires—is employed to pin the DWs. The depinning field of the DW initially pinned at the notch is then measured with respect to H _T. Interestingly, it is experimentally found that the depinning field is drastically decreased to almost 0 with increasing H _T, due to the internal shift of the DW position at the notch. Moreover, it is experimentally observed that an oscillatory behavior of the depinning field occurs with respect to H _T, Micromagnetic calculation is performed to model the depinning behavior of the DW pinned at the notch structure with respect to H _T. It is ascribed to the natural edge roughness of the nanowire, which means the edge roughness plays an important role in determination of the depinning field.