AC MOKE Measurements of Yttrium Iron Garnet Thin Films

The traditional magneto-optical Kerr effect (MOKE) measurements involve measuring the intensity of a light reflected off the samples subjected to a DC magnetic field. By superimposing an AC field to the sweeping DC field, and measuring the AC component of the light intensity, we achieved a high signal-to-noise ratio and a better resolution in determining the Curie temperatures of magnetic samples. For a demonstration, we have determined the Curie temperature of a 350 nm thick YIG (yttrium iron garnet, Y₃Fe5O12) thin film to be 511.0 +/− 0.5 K using this method.