Patent ID: 7148531

Claim:
A ferromagnetic material thin-film based digital memory, said memory comprising: a substrate formed of a base supporting an electrically insulating material primary substrate layer; a plurality of current control devices, each supported on said primary substrate layer and having an interconnection structure portion extending substantially parallel to said primary substrate layer with each of said plurality of current control devices being separated from one another by spacer material therebetween, said plurality of current control devices being electrically interconnected with information storage and retrieval circuitry, a plurality of bit structures, each supported on and electrically connected to a said interconnection structure portion of a corresponding one of said plurality of current control devices and separated from one another by a spacer material therebetween, 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; 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 interconnection structure portion providing support thereto, said information storage and retrieval circuitry for drawing a sufficient electrical current selectively through each said bit structure, that said interconnection structure portion providing support thereto and that said one of said plurality of current control devices from which that said interconnection structure portion extends to cause substantial heating of that said bit structure to thereby 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 primary substrate layer and said spacer material positioned thereabout.