Plumeria Investments, Inc.

Other

Magnetic Semiconductors

Juan Monico

James Gustav Harris

Joseph S McDowell

Otto Voegli

The present invention, generally speaking, provides a magnetic memory element that is single domain in nature and has a geometry that mitigates the effects of half-select noise. In a preferred embodiment, the magnetic memory element takes the form of a magnetic post or tube having an aspect ratio in the range of 2:1 (more preferably 4:1). The outside diameter of the magnetic tube or post is preferably less than 0.8 microns, more preferably 0.6 microns or less. The magnetic post or tube then functions as a single magnetic domain. In the case of a magnetic tube, the skin of the tube is formed of a magnetic material and the interior of the tube is formed of a non-magnetic material. Suitable non-magnetic materials include copper, gold and silicon. The coercivity of the magnetic tube structure may be adjusted by adjusting the thickness of the magnetic skin. As a result, the magnetic memory element is readily scalable to smaller geometries as lithographic techniques improve. The combination of very small, single-domain size and a relatively large aspect ratio results in uniquely desirable properties. Current levels within any reasonable expectation operate to switch the state of the magnetic tube only when the magnetic tube is destabilized by running current through it. With current flowing through the magnetic tube, its state may be readily changed by running modest currents in opposite directions through two parallel conductors, one on each side of the magnetic tube. When the magnetic tube is switched, the single domain nature of the magnetic tube produces a signal that is typically 10-15 times stronger than signals produced by conventional magnetic memory elements. The magnetic tube functions as a vertical magnetic field generator and may be formed in intimate proximity to a magnetic field sensor such as above the gate of a magFET.

High-efficiency miniature magnetic integrated circuit structures

High efficiency miniature magnetic integrated circuit structures

Magnetic integrated circuit structures exhibit desirable characteristics for purposes of realizing a magnetic semiconductor memory. In combination with a carrier-deflection-type magnetic field sensor, each of a variety of magnet structures realize a condition in which the magnetic field is substantially orthogonal to the direction of travel of carriers of a sense current, thereby achieving maximum sensitivity. In general, the magnetic structures are highly efficient and achieve a high degree of control of the magnetic field. As a result, a minimum-size device such as a MOS device suffices for purposes of sourcing a magnetizing current. By basing a magnetic memory cell on a single minimum-size MOS device, a small cell may be realized that compares favorably with a conventional DRAM or FLASH memory cell. The greater degree of control over the magnetic field afforded by the magnetic structures enables cross-coupling between cells in a memory array to be minimized.

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San Jose, CA, United States of America

Juan Monico