Domain tip propagation logic

Abstract

A new thin film technique is described which has implications for use in a network of all-magnetic logic. The technique, called domain tip propagation logic (DTPL), makes use of the controlled growth of domains within low coercive force channels imbedded in a film element of generally high coercive force. Information is stored within regions of the low coercive force channels in the form of domains of reversed magnetization and propagated through the channels under the influence of an applied field by expansion of the domains at the domain tips. The direction of domain tip propagation can be controlled and the mutual interaction between domain tips within channels brought into proximity of each other. The direction of domain tip propagation is sensitive to the magnitude and direction of the applied field. This has made it possible to design new types of thin film shift registers which are of essentially unlimited length and high storage density and speed. Experimental DTPL shift registers with linear bit densities of 100 bits per inch have been constructed and operated with 300-ns clock pulses. As a result of these tests, it appears that the construction of multimegacycle DTPL shift registers with storage densities of the order of several thousands of bits per square inch is feasible. Magnetostatic interactions between channeled domain tips make any combinational operation possible and lead quite naturally to the construction of all the usual logic elements in a variety of ways. Information transfer is possible with what is essentially unlimited fan-out so that there is no need for regeneration in building up large complexes of logic. The restriction of reversal of the magnetization to small regions of film permits a high density of memory and logic elements. The principles of operation of various devices utilizing DTPL are described, as well as the techniques of device fabrication. Some of the static and dynamic properties of channeled domain tips which are pertinent to the operation of the devices presented will be discussed.