Multi-state magnetoresistance random access cell with improved memory storage density
First Claim
1. A multi-state magnetoresistive random access memory device having a resistance, the device comprising:
- a substrate;
a first conductive line positioned on the substrate;
a fixed ferromagnetic region positioned proximate to the first conductive line, the fixed ferromagnetic region having a fixed magnetic moment vector fixed in a preferred direction both with and without an applied magnetic field;
a non-ferromagnetic spacer layer positioned on the fixed ferromagnetic region;
a free ferromagnetic region positioned on the non-ferromagnetic spacer layer, the free ferromagnetic region having a free magnetic moment vector that is free to rotate in the presence of an applied magnetic field and where the free ferromagnetic region has an anisotropy that creates more than two stable positions for the free magnetic moment vector wherein the more than two stable positions are oriented relative to the preferred direction of the fixed magnetic moment vector such that each position produces a unique resistance; and
a second conductive line positioned at a non-zero angle to the first conductive line.
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Abstract
A multi-state magnetoresistive random access memory device having a pinned ferromagnetic region with a magnetic moment vector fixed in a preferred direction in the absence of an applied magnetic field, an non-ferromagnetic spacer layer positioned on the pinned ferromagnetic region, and a free ferromagnetic region with an anisotropy designed to provide a free magnetic moment vector within the free ferromagnetic region with N stable positions, wherein N is a whole number greater than two, positioned on the non-ferromagnetic spacer layer. The number N of stable positions can he induced by a shape anisotropy of the free ferromagnetic region wherein each N stable position has a unique resistance value.
66 Citations
29 Claims
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1. A multi-state magnetoresistive random access memory device having a resistance, the device comprising:
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a substrate; a first conductive line positioned on the substrate; a fixed ferromagnetic region positioned proximate to the first conductive line, the fixed ferromagnetic region having a fixed magnetic moment vector fixed in a preferred direction both with and without an applied magnetic field; a non-ferromagnetic spacer layer positioned on the fixed ferromagnetic region; a free ferromagnetic region positioned on the non-ferromagnetic spacer layer, the free ferromagnetic region having a free magnetic moment vector that is free to rotate in the presence of an applied magnetic field and where the free ferromagnetic region has an anisotropy that creates more than two stable positions for the free magnetic moment vector wherein the more than two stable positions are oriented relative to the preferred direction of the fixed magnetic moment vector such that each position produces a unique resistance; and a second conductive line positioned at a non-zero angle to the first conductive line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 19, 20, 21, 22)
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16. A multi-state magnetoresistive random access memory device comprising:
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a substrate; a first conductive line positioned proximate to the base electrode; a free ferromagnetic region positioned proximate to the first conductive line, the free ferromagnetic region having a free magnetic moment vector that is free to rotate in the presence of an applied magnetic field and where the free ferromagnetic region has an anisotropy that creates more than two stable positions for the free magnetic moment vector wherein the more than two stable positions are oriented relative to the preferred direction of the fixed magnetic moment vector such that each position produces a unique resistance; a non-ferromagnetic spacer layer positioned on the free ferromagnetic region; a fixed ferromagnetic region positioned on the non-ferromagnetic spacer layer, the fixed ferromagnetic region having a fixed magnetic moment vector fixed in a preferred direction both with and without an applied magnetic field; and a second conductive line positioned at a non-zero angle to the first conductive line. - View Dependent Claims (17, 23, 24, 25, 26, 27, 28, 29)
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Specification