Device for close-packed magnetic domains

A device for storing digital information in the form of magnetic domains, comprising:

• a control device having an information input terminal;
• a non-magnetic substrate layer;
• a first layer of magnetic material, structurally integral with said substrate layer;
• a second layer of magnetic material, structurally integral with said first layer of magnetic material;
• a bias magnetic field generator for producing a magnetic field extending transverse to said first and second layers for sustaining magnetic domains therein;
• first magnetic domain generating means operative at a first position for locally and sequentially producing a first series of magnetic domains in said first layer;
• second magnetic domain generating means operative at a second position for locally and sequentially and synchronously with said first domain generating means producing a second series of magnetic domains in said second layer;
• propagation means for moving magnetic domains away from the first and second domain generating means in synchronism with said first domain generating means;
• said control device controlling said first and second domain generating means for selectively forming single magnetic domains or superposed magnetic domain pairs in said first and second layers of magnetic material, superposed magnetic domain pairs comprising a magnetic compensation wall at their interface, all single magnetic domains and superposed magnetic domain pairs being mutually repulsive including a force component in the plane of said layers;
• said first and second layers each comprising at least two magnetic crystalline sublattices with first and second magnetizations which have substantially opposite directions, corresponding sublattices within said first and second layers having magnetizations in opposite directions at locations where there are no magnetic domains in either layer;
• detector means for the separate detection of single magnetic domains and superposed magnetic domain pairs;
• annihilation means for destroying single magnetic domains and superposed magnetic domain pairs;
• a first shift register for serially receiving single magnetic domains or superposed magnetic domain pairs generated by said first and second domain generating means;
• a two-dimensional domain array region, having a lattice of domain positions, situated adjacent the first shift register;
• coincident propagation means for the coincident driving of a row of magnetic domains from said first shift register transversely into the domain array region;
• and
• confinement means for bounding the domain array region on edges thereof which are transverse to said first shift register, and on an edge which is remote from said first shift register;
• wherein said control device activates said coincident propagation means at instants separated by intervals corresponding to integral numbers of half periods of the propagation means, said intervals having at least a predetermined minimum value for the successive formation of an array of rows of magnetic domains in directions along said first shift register in the domain array region.