Depinning of vortex domain walls from an asymmetric notch in a permalloy nanowire

The mechanism of depinning process of vortex domain wall (DW) in a planar magnetic nanowire with an asymmetric notch is investigated by using focused magneto-optical Kerr effect (MOKE) magnetometer and micromagnetic modeling. Two distinct depinning fields are directly observed by the single-shot MOKE measurements. Micromagnetic modeling provides physical insight into the details of how the depinning process develops at the asymmetric notch and reveals that the different depinning fields originate from the different chiralities of the vortex DWs.