Annular GMR-based memory element
First Claim
1. A non-volatile ferromagnetic random access memory element comprising:
- a first ferromagnetic ring and a second ferromagnetic ring, wherein one of said ferromagnetic rings is hard or antiferromagnetically-pinned and the other ferromagnetic ring is magnetically softer than said hard or antiferromagnetically-pinned ring;
a non-magnetic conductive layer sandwiched between and contacting said first and second ferromagnetic rings, for preventing essentially all exchange coupling between said first and second ferromagnetic rings;
a first end nonmagnetic conducting layer at one end of said ferromagnetic random access memory element;
a second end nonmagnetic conducting layer at an opposite end of said non-volatile ferromagnetic random access memory element;
said first and second end conducting layers defining a conductive path for flowing a current from said first ferromagnetic ring, through said nonmagnetic conductive layer, to said second ferromagnetic ring, said conductive path being perpendicular to a magnetic moment of at least one of said first and second ferromagnetic rings.
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Accused Products
Abstract
A memory element has a sandwich structure in which rings of ferromagnetic material are spaced apart by a layer of a non-magnetic conductor (which is also typically a ring). These ferromagnetic rings will have differing magnetic hardness. At least one ring will be magnetically hard or antiferromagnetically-pinned. At least one other ring will be magnetically softer than the hard or antiferromagnetically-pinned ring. The non-magnetic conductor is at least thick enough to prevent essentially all exchange coupling between the ferromagnetic rings. Conducting leads provide current to pass through the ferromagnetic rings, perpendicular to magnetic moments in the ferromagnetic rings.
218 Citations
21 Claims
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1. A non-volatile ferromagnetic random access memory element comprising:
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a first ferromagnetic ring and a second ferromagnetic ring, wherein one of said ferromagnetic rings is hard or antiferromagnetically-pinned and the other ferromagnetic ring is magnetically softer than said hard or antiferromagnetically-pinned ring; a non-magnetic conductive layer sandwiched between and contacting said first and second ferromagnetic rings, for preventing essentially all exchange coupling between said first and second ferromagnetic rings; a first end nonmagnetic conducting layer at one end of said ferromagnetic random access memory element; a second end nonmagnetic conducting layer at an opposite end of said non-volatile ferromagnetic random access memory element; said first and second end conducting layers defining a conductive path for flowing a current from said first ferromagnetic ring, through said nonmagnetic conductive layer, to said second ferromagnetic ring, said conductive path being perpendicular to a magnetic moment of at least one of said first and second ferromagnetic rings. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 19)
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14. An array of non-volatile ferromagnetic random access memory elements, comprising:
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a first row of at least two non-volatile ferromagnetic random access memory elements; each of said non-volatile ferromagnetic random access memory elements having upper and lower surfaces and including; (i) a first ferromagnetic ring and a second ferromagnetic ring, wherein one of said ferromagnetic rings is hard or antiferromagnetically-pinned and the other ferromagnetic ring is magnetically softer than said hard or antiferromagnetically-pinned ring; (ii) a non-magnetic conductive layer sandwiched between said first and second ferromagnetic rings; a first conducting lead extending across and physically contacting said upper surfaces of each of said at least two non-volatile ferromagnetic random access memory elements in said first row; a second conducting lead, transverse to, but not contacting, said first conducting lead, extending across and physically contacting only a first one of said at least two non-volatile ferromagnetic random access memory elements in said first row at said lower surface of said first one of said ferromagnetic random access memory elements in said first row, said first and second conducting leads defining a conductive path for flowing a current from said first magnetic layer, through said nonmagnetic metallic layer, to said second magnetic layer, said conductive path being perpendicular to closed magnetic currents in said ferromagnetic rings. - View Dependent Claims (15, 16, 17, 18)
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20. A method of storing digital data, comprising the steps of:
setting a bit of data as either a "0" or "1" in a non-volatile ferromagnetic random access memory element including; a first ferromagnetic ring and a second ferromagnetic ring, wherein one of said ferromagnetic rings is hard or antiferromagnetically-pinned and the other ferromagnetic ring is magnetically softer than said hard or antiferromagnetically-pinned ring, and said ferromagnetic rings are poled so that the easy axes of the magnetic moments of said rings are oriented to be either clockwise or counterclockwise with respect to said rings and have magnetizations forming closed magnetic circuits about said rings; a nonmagnetic conducting layer sandwiched between said first and second ferromagnetic rings; a first end nonmagnetic conducting layer at one end of said non-volatile ferromagnetic random access memory element; and a second end nonmagnetic conducting layer at an opposite end of said non-volatile ferromagnetic random access memory element; by exposing said non-volatile ferromagnetic random access memory element to magnetic field which sets said magnetic moment of said softer ferromagnetic ring to be either parallel or antiparallel to said magnetic moment of said hard or antiferromagnetically-pinned ferromagnetic ring, wherein resistance across said non-volatile ferromagnetic random access memory element after the application of said field is set as a "0" or "1". - View Dependent Claims (21)
Specification