Anomalous Hall-Effect Measurements Of Domain Writing And Erasure In Magnetooptic Thin-Films

The thermomagnetic writing and erasure of submicron domains has been observed in a magneto-optic thin film using the anomalous Hall effect (AHE) voltage generated within the medium itself. A TbFeCo film has been photolithographically patterned to form a cross-shaped Hall geometry a few microns across. The AHE voltage, proportional to a weighted average of the transition metal magnetization within the cross, is affected by a laser pulse in two ways. First, the laser heats the film, reducing the magnitude of the magnetization. Secondly, the sign of the AHE voltage changes as the magnetization reverses within the written domain. A time resolution if 100 ns, has been obtained, and better than 10 ns resolution should be achievable. The technique has been used to make quantitative laser-induced writing as a function of laser pulse energy and external field