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Improved Reading and Writing Scheme for a Vortex File Memory

IP.com Disclosure Number: IPCOM000050762D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 43K

Publishing Venue

IBM

Related People

Faris, SM: AUTHOR [+2]

Abstract

Vortex file memories using storage and transportation of vortices in Type II superconductors have been proposed, promising potentially high data rates as well as high density. In these schemes the vortices are manipulated in a manner analogous to magnetic bubbles. For example, a major-minor loop organization is one method by which writing and nondestructive reading can be carried out. This method requires that the transfer of bits (vortices) be carried out by special complex geometrical configurations and vortex guiding structures, and depends on ideal material properties, especially with regard to pinning sites.

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Improved Reading and Writing Scheme for a Vortex File Memory

Vortex file memories using storage and transportation of vortices in Type II superconductors have been proposed, promising potentially high data rates as well as high density. In these schemes the vortices are manipulated in a manner analogous to magnetic bubbles. For example, a major-minor loop organization is one method by which writing and nondestructive reading can be carried out. This method requires that the transfer of bits (vortices) be carried out by special complex geometrical configurations and vortex guiding structures, and depends on ideal material properties, especially with regard to pinning sites.

It is proposed to simplify the organization of the vortex memory and eliminate possible material constraints, such as pinning forces, imposed on the vortex guiding structures. The memory is shown in Fig. 1, in which an array of circular holes 12 is made in the ground plane 10, with diameter and period chosen such that a Josephson weak link 14 is created between two adjacent holes. Circular holes 12 are storage sites for vortices since they represent regions of lowest energy (potential wells). Each weak link between two potential wells presents a potential barrier to the stored vortices in those wells. This potential barrier can be eliminated when the weak link switches to the voltage tate. Vortex generators G and detectors D write and read the vortices.

The meandering control line 16 carries a transport current I(T). Current I(GT) also flows in the ground plane through the weak links. When a weak link carries I(T) and I(CIR) (for a stored vortex) and I(GT), its threshold is exceeded, its barrier is lowered, and the Lorentz force moves the vortex to an adjacent potential well where it encounters a high potential barrier to prevent it from moving further. The higher potential barrier is created due to the fact that I(T) is now flowing in the opposite direction. (Zig-zagging control line 16 causes the current to flow in opposite directions between adjacent wells.) Thus, the Lorentz force acts in a direction opposite to that of the previous vortex motion.

Fig. 2 is a side view showi...