Time-resolved observation of Barkhausen avalanche in Co thin films using magneto-optical microscope magnetometer

We develop an experimental technique for direct, full-field, time-resolved observation of the Barkhausen avalanche in a two-dimensional thin-film system, using a magneto-optical microscope magnetometer (MOMM). Real-time visualization capability of the MOMM enables us to microscopically observe all the details of the Barkhausen avalanche in Co thin films, which is not feasible using other indirect experimental techniques adopted so far. We find that there exist fluctuating flexible domain walls deformed by defects and that, interestingly enough, the domain wall exhibits still-detectable fluctuation even around a strong linear defect as well as a strong point-like defect, from which we conclude that a critical avalanche continues to exist even in strong pinning cases. © 2003 American Institute of Physics.