Suitability of MnBi and Mn1-xTixBi films for magnetooptic memories

For a magnetooptic memory with nonholographic Curie temperature writing and Faraday rotation reading the energy necessary for writing a bit and the signal efficiency of the read process are regarded theoretically. It is shown that it is not sufficient to characterize the magnetooptical properties by the ratio F/α of the specific Faraday rotation F and the absorption coefficient α. F - α combinations in a limited region of the F - α plane are required instead. Based on these considerations, the requirements concerning the properties of magnetooptic storage films are evaluated and compared in detail with the properties observed experimentally for MnBi and Mn0.8Ti0.2Bi films. Mn0.8Ti0.2Bi films with the high-temperature phase sufficiently stable from room temperature up to well above the Curie temperature are of especial interest for magnetooptic memories.