Thermomagnetic switching in amorphous rare-earth transition metal alloys

Abstract

Conditions for writing and erasure have been investigated for different amorphous rare-earth transition metal alloys using a simple temperature distribution evaluated for a three-layer structure. The radial and time dependence of the magnetic parameters relevant for the switching process have been calculated by means of the mean-field theory based on experimental data of the saturation magnetization, uniaxial anisotropy, and the coercivity, for alloys of composition (Gd,Tb)1−xFex and Tb1−x(Fe,Co)x. From the radial profiles of the coercive field, maximum domain diameters are extracted in the limit of large domain velocities. Domain-wall stabilities are calculated from the force equation for writing and erasure conditions as a function of applied field yielding margins for stable domains and collapse fields. In addition to bubblelike domains, ring domain configurations are considered, which imply the possibility of direct overwrite for alloys with a compensation temperature above ambient temperature. The switching with a continuous read power level is discussed.