Patent ID: 6963098

Claim:
A ferromagnetic thin-film based digital memory, said memory comprising: a substrate; a plurality of bit structures, each supported on said substrate and separated from one another by spacer material therebetween, that are electrically interconnected with information storage and retrieval circuitry, said bit structures each comprising a first magnetic material film in which a characteristic magnetic property is substantially maintained below a first critical temperature above which such magnetic property is not maintained and a second magnetic material film in which a characteristic magnetic property is substantially maintained below a second critical temperature above which such magnetic property is not maintained, and with said second magnetic material film being separated from said first magnetic material film by at least one intermediate layer of a nonmagnetic material having two major surfaces on opposite sides thereof, said bit structures each having a first interconnection structure providing electrical contact thereto positioned against a first contact surface thereof substantially parallel to said intermediate layer major surfaces and also between said first contact surface and said substrate; and a plurality of word line structures each having a pair of word line end terminal regions adapted to conduct electrical current in at least one direction therethrough, each of said pairs of word line end terminal regions having an electrical conductor electrically connected therebetween which is located on an opposite side of said intermediate layer of a corresponding one of said bit structures from said first interconnection structure providing electrical contact thereto, said information storage and retrieval circuitry for drawing a sufficient electrical current selectively through each said bit structure and said first interconnection structure providing electrical contact thereto to cause substantial heating of that said bit structure to raise temperatures thereof to have at least one of said first and second magnetic material films therein at least approach its corresponding one of said first and second critical temperatures while being substantially above temperatures of at least an adjacent said bit structure because of sufficient extent of, and smallness of thermal conductivities of, at least portions of said selected bit structure and of those portions of said substrate and said spacer material positioned thereabout.