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Memory Device Using Anisotropic Metal Keeper

IP.com Disclosure Number: IPCOM000093978D
Original Publication Date: 1966-Apr-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Anacker, W: AUTHOR

Abstract

In this coupled-easy-axis magnetic film memory device, a portion of the usual isotropic ferrite keeper is replaced by an anisotropic metal keeper. Such is in order to improve the flux closure and to obtain more efficient switching.

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Memory Device Using Anisotropic Metal Keeper

In this coupled-easy-axis magnetic film memory device, a portion of the usual isotropic ferrite keeper is replaced by an anisotropic metal keeper. Such is in order to improve the flux closure and to obtain more efficient switching.

In this CEA film device, the word line is plated on three sides with a keeper film made of a high-permeability, anisotropic metal such as permalloy. A layer of insulation such as silicon monoxide separates the word line and its keeper film from the storage film on the upper surface of the bit-sense line. The metal keeper film has an easy axis extending longitudinally of the word line and parallel with the easy axis of the storage films.

This keeper film has a thickness at least twice that of each storage film and its magnetization normally is in a split-up, antiparallel state along the easy axis of this film. The spaces between adjacent word lines are filled with an isotropic ferrite material which, because it is nonconductive, can extend into contact with the upper storage film as shown.

During the application of the word drive, the bulk of the hard-direction flux from the storage films is closed entirely through the metal keeper film. Due to the greater thickness of this keeper film, complete hard-direction flux closure can be achieved without rotating the magnetic moments of the keeper film more than about 30 degrees from the keeper easy axis as indicated in the lower drawing. Thus a rota...