Thermomagnetic writing on exchange-coupled amorphous rare-earth iron double-layer films

Amorphous double-layer films are prepared by co-evaporation technique. One layer of the film is for thermomagnetic writing made of 500A thick Tb-Fe or Dy-Fe, and the other for magneto-optic readout made of 150 or 300A thick Gd-Fe. The magnetizations of the layers are coupled with each other through the exchange force. The strong coupling brings a high switching field to the readout layer. The exchange-coupled Gd-Fe/ Tb-Fe film exhibits low writing energy and high bit density nearly the same as those of Tb-Fe films, and exhibits magneto-optic Kerr effect as high as Gd-Fe films.