Abstract: The temperature variation of the bubble collapse field of a class of garnet magnetic bubble layer materials is selected by control of octahedral site substitution during layer growth. This permits the growth of layers, whose temperature dependence of critical magnetic properties more closely match the temperature dependence of bias magnet materials, resulting in extended operating temperature range and/or wider operating margins (with attendant improvement in manufacturing yield). Layer growth at higher temperature results in a larger rate of change of collapse field by producing greater octahedral occupation of predominantly tetrahedrally coordinated germanium.

Abstract: The temperature variation of the bubble collapse field of a class of garnet magnetic bubble layer materials is selected by control of octahedral site substitution during layer growth. This permits the growth of layers, whose temperature dependence of critical magnetic properties more closely matches the temperature dependence of available bias magnet materials, resulting in extended operating temperature range and/or wider operating margins (with attendant improvement in manufacturing yield). A preferred substitution species is lutetium, known as a dodecahedral site occupant, for which it has been determined that a significant and controllable octahedral occupancy can be produced by suitable choice of growth conditions.

Abstract: Members of a particular class of magnetic garnet compositions show characteristics useful for incorporation in magnetic memory devices which depend for their operation on the positioning of single wall domains ("bubbles"). Such compositions, ordinarily in the form of a supported layer, manifest high limiting bubble velocity, thereby making possible high record and access rates. Tetrahedral iron sites in the concerned compositions are occupied by non-magnetic ions in amount such as to result in magnetically balanced iron sub-lattices so that the magnetic moment contribution is made primarily by dodecahedral site ions. Europium is a necessary dodecahedral site occupant. High limiting velocity is attributed to the high value of the gyromagnetic ratio (g value) associated with europium.