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 (Ni(80) Fe(20)) nanowires (>= 400 nm width and >= 20 nm thickness) in real time. By probing the DW motion within the 1 mu m 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.