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Coupled Film Memory Device Using Films of Different Thickness

IP.com Disclosure Number: IPCOM000093980D
Original Publication Date: 1966-Apr-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Keefe, GE: AUTHOR

Abstract

In coupled-film memory device C of the closed-easy-axis CEA type, the top film is substantially thicker than the bottom film. Device C performs better than a CEA memory device A or B in which both the top and bottom films have the same thickness.

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Coupled Film Memory Device Using Films of Different Thickness

In coupled-film memory device C of the closed-easy-axis CEA type, the top film is substantially thicker than the bottom film.

Device C performs better than a CEA memory device A or B in which both the top and bottom films have the same thickness.

Where the two magnetic films of a coupled-film device are of equal thickness and are relatively wide in comparison with their separation, as in device A above, the uncancelled demagnetizing fields of the two films are negligible. Hence these films are not sensitive to bit-disturb pulses. However, such a memory device requires relatively high bit currents and its construction is not conducive to a high bit density of the stored information. On the other hand, if the strip line and films are made narrow, as in device B, then the respective uncancelled demagnetizing fields of the films increases. The net demagnetizing field is proportional to:

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In a CEA memory device the bottom film customarily is enclosed by the loop of the bit-sense line. The top film is outside of this loop. Hence it is customary to regard the bottom film as the storage film and the top film as its keeper. During a read operation it is the bottom film which contributes most of the sense signal. During a write operation it is this film which is most susceptible to bit-write disturbances. For this reason it is very desirable to cancel the demagnetizing field which acts upon the bo...