Abstract: An optical recording disc in which a disc substrate made of a synthetic resin having a light transmittance and a hub made of a synthetic resin, fixed to a center part of the disc substrate by means of a predetermined technique such as a supersonic wave expansion molding and on which a circular magnetic metal plate is installed by means of an insert molding and so on are provided and a circular groove which is continuous at an outer peripheral side of a fixing part between the disc substrate and hub is furthermore installed on at least either of the disc substrate or hub. The groove is provided for absorbing a stress generated due to a difference in thermal expansion rates between the disc substrate made of the snythetic resin and magnetic metal plate.

Abstract: An optomagnetic recording medium utilizing both rare earth metals and transition metals in the optomagnetic recording system. From 15 to 35 atomic % of the recording medium on the nonmagnetic base consists of one of the rare earth metals gadolinium (Gd), terbium (Tb) or dysprosium (Dy) with the balance being an alloyed mixture of iron (Fe), cobalt (Co) and germanium (Ge). The optomagnetic recording material of the present invention has an increased phase transition temperature without a rise in its Curie point, and provides satisfactory recording and erasing under temperature conditions up to near the Curie point.