Single shot Kerr magnetometer for observing real-time domain wall motion in permalloy nanowires

Details are presented of a single shot focused magneto-optic Kerr effect (MOKE) magnetometer which is used to capture the movement of single domain walls (DWs) in permalloy (Ni80 Fe20) nanowires in real time. By probing the DW motion within the 1μm diameter laser spot of the instrument, DW velocity and pinning field distributions were obtained. An external field was ramped up linearly, and depinning of a DW from the same start position was observed at three different fields, indicating the stochastic nature of the DW motion.