Kerr Readout Characteristics of Gd–Fe, Tb–Fe and Dy–Fe Amorphous Alloy Films

The Kerr readout characteristics of Gd–Fe, Tb–Fe and Dy–Fe amorphous films were investigated using a differential detection system. In the present detection system, a primary factor to limit the S / N is the reduction of the Kerr rotation angle for Tb–Fe and Dy–Fe films caused by the decrease of the iron sublattice magnetization with increasing temperature during the readout, while it is the reduction of the detector sensitivity for Gd–Fe films. The obtained maximum values of the S / N were 20, 10 and 4 for Gd–Fe, Tb–Fe films, respectively.