Spin-transfer based MRAM with reduced critical current density
First Claim
1. A magnetic random access memory device comprising:
- a fixed magnetic element;
a free magnetic element having a first magnetization and a first anisotropy;
an insulator positioned between the fixed magnetic element and the free magnetic element; and
a keeper layer positioned contiguous to the free magnetic element and having a second anisotropy orthogonal to the first anisotropy.
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Accused Products
Abstract
A magnetic random access memory device comprises a spin torque MRAM cell (100) having a reduced switching current (Ic) wherein standard materials may be used for a free layer (108). A fixed magnetic element (112) polarizes electrons passing therethrough, and the free magnetic element (108) having a first plane anisotropy comprises a first magnetization (130) whose direction is varied by the spin torque of the polarized electrons. An insulator (110) is positioned between the fixed magnetic element (112) and the free magnetic element (108), and a keeper layer (104) positioned contiguous to the free magnetic element (108) and having a second plane anisotropy orthogonal to the first plane anisotropy, reduces the first plane anisotropy and hence reduces the spin torque switching current (Ic). The keeper layer (104) may comprise alternating synthetic antiferromagnetic layers (132, 134) of magnetization approximately equal in magnitude and opposite in direction.
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Citations
20 Claims
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1. A magnetic random access memory device comprising:
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a fixed magnetic element; a free magnetic element having a first magnetization and a first anisotropy; an insulator positioned between the fixed magnetic element and the free magnetic element; and a keeper layer positioned contiguous to the free magnetic element and having a second anisotropy orthogonal to the first anisotropy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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10. A magnetic random access memory device comprising:
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a fixed magnetic element that polarizes electrons passing therethrough; a free magnetic element having a first magnetization whose direction is varied by the spin torque of the polarized electrons, and having a first anisotropy; an insulator positioned between the fixed magnetic element and the free magnetic element; and a keeper layer positioned contiguous to the free magnetic element that reduces the first anisotropy, the keeper layer having a second anisotropy orthogonal to the first anisotropy, wherein a spin torque current is reduced by the reduction of the first plane anisotropy. - View Dependent Claims (9, 11, 12, 13, 14, 15, 16, 17)
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18. A method for writing data to a magnetic random access memory device comprising a plurality of cells, each comprising a fixed magnetic element having a first fixed magnetization and a free magnetic element having a second variable magnetization and a first anisotropy, the method comprising:
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selecting a cell; applying a write current to the selected cell; switching orientation of the second variable magnetization to a written state in response to the write current; and reducing the first anisotropy. - View Dependent Claims (19, 20)
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Specification