Novel memory based on use of magnetic wires with re-entrant hysteresis loops

Magnetic wires possessing highly re-entrant hysteresis loops can be utilized as general purpose memory elements. Information is stored by locating a reversal of magnetization in either of two positions along a length of wire corresponding to the memory region. There are a number of different memory configurations possible. Several of these have been built and found to operate with large margins. The element is relatively slow, with practical cycle times greater than 10 μs, but it lends itself to inexpensive construction techniques. The high ratios attainable between nucleation and wall motion threshold fields are reflected in similarly high drive current margins and, consequently, hold promise of a high yield in manufacture and thereby low cost. The effective memory speed can be increased by the use of fast nondestructive readout. A unique feature of the element is that time coincidence of drive pulses is unnecessary.