Propagation of cylindrical magnetic domains in orthoferrites

Bits of information, represented by cylindrical magnetic domains in a thin platelet of orthoferrite magnetized normal to the platelet, can be propagated by applying a rotating uniform transverse magnetic field to magnetize a structured soft magnetic overlay placed in the same plane as the orthoferrite. Typically, the orthoferrite platelets are 2 mils thick and the domains are 1 to 2 mils in diameter. The structured overlay can be an etched pattern of 1- by 5-mil 5000-Å-thick evaporated Permalloy rectangles, requiring transverse fields on the order of 10 Oe. A bit packing density between 10⁴and 10⁵bits/in²can be achieved using 1-mil domains and a bit rate of 1 MHz is believed possible. Because of the structural simplicity of devices using propagating cylindrical domains driven by uniform fields, they are economically attractive. Another feature is that logic can be performed within the device by utilizing the interaction between domains.