PURPOSE: To raise Curie temperature without decreasing a Kerr rotating angle by forming an amorphous four-dimensional alloy thin film by using Gd, Dy, Tb, and Fe while specifying the atom ratio of the sum of Gd, Dy and Tb and the ratio of Gd and Dy within prescribed ranges respectively.

CONSTITUTION: An amorphous four-dimensional alloy thin film which has an easy magnetization axis perpendicular to the film surface is formed by Gd, Dy, Tb, and Fe. In this case, the atom ratio of the sum of Gd, Dy and Tb is set to 15W35atom%, and the ratio of Gd and Dy is set to 0W50atom%. Consequently, a Curie temperature is raised without decreasing a Kerr rotating angle, thereby improving an S/N ratio and recording density.