Anomalous Hall Effect Measurements of Domain Writing and Erasure in Magneto-Optic Thin-Films

The thermomagnetic writing and erasure of sub-micron 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 A HE voltage changes as the magnetization reverses within the written domain. Time resolution is currently 100 ns, better than 10 ns resolution should be achievable. The technique has been used to make quantitative measurements of domain size and temperature profile during laser induced writing as a function of laser pulse energy and external field. © 1990 IEEE