Observation of Barkhausen noise in a 20 x 20 mu m permalloy thin film square dot

Barkhausen jumps in the magnetic hysteresis loop of a single permalloy thin film square dot of 20 x 20 mum in size and 80 nm thick have been observed, for the first time, with a magneto-optical ellipsometer which is capable t o record a complete loop in time of seconds and in a single sweep of applie d field, About 6000 loops have been measured and separately recorded: each loop is different from the others. The statistical properties of the Barkha usen jumps are presented and discussed.