Spin-transfer multilayer stack containing magnetic layers with resettable magnetization
First Claim
1. A magnetic element, comprising:
- a resettable layer having a first magnetization that is set in a selected direction by at least one magnetic field, each magnetic field being generated externally to the resettable layer;
a storage layer having at least one magnetic easy axis and having a second magnetization that changes direction based on a spin-transfer effect when a write current passes through the magnetic element; and
a spacing layer formed between the resettable layer and the storage layer.
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Abstract
A magnetic element for a high-density memory array includes a resettable layer and a storage layer. The resettable layer has a magnetization that is set in a selected direction by at least one externally generated magnetic field. The storage layer has at least one magnetic easy axis and a magnetization that changes direction based on the spin-transfer effect when a write current passes through the magnetic element. An alternative embodiment of the magnetic element includes an additional multilayer structure formed from a tunneling barrier layer, a pinned magnetic layer and an antiferromagnetic layer that pins the magnetization of the pinned layer in a predetermined direction. Another alternative embodiment of the magnetic element includes an additional multilayer structure that is formed from a tunneling barrier layer and a second resettable layer having a magnetic moment that is different from the magnetic moment of the resettable layer of the basic embodiment.
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Citations
80 Claims
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1. A magnetic element, comprising:
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a resettable layer having a first magnetization that is set in a selected direction by at least one magnetic field, each magnetic field being generated externally to the resettable layer;
a storage layer having at least one magnetic easy axis and having a second magnetization that changes direction based on a spin-transfer effect when a write current passes through the magnetic element; and
a spacing layer formed between the resettable layer and the storage layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A magnetic memory having a plurality of magnetic cells, at least one magnetic cell including a magnetic element comprising:
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a resettable layer having a first magnetization that is set in a selected direction by at least one magnetic field, each magnetic field being generated externally to the resettable layer;
a storage layer having at least one magnetic easy axis and having a second magnetization that changes direction based on a spin-transfer effect when a write current passes through the magnetic element; and
a spacing layer formed between the resettable layer and the storage layer. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. A method for forming a magnetic element, the method comprising steps of:
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forming a resettable layer having a first magnetization that is set in a selected direction by at least one magnetic field, each magnetic field being generated externally to the resettable layer;
forming a storage layer having at least one magnetic easy axis and having a second magnetization that changes direction based on a spin-transfer effect when a write current passes through the magnetic element; and
forming a spacing layer between the resettable layer and the storage layer. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60, 61, 62, 63)
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64. A method for writing information to a magnetic element, the magnetic element including a resettable layer having a first magnetization that is set in a selected direction by at least one magnetic field, each magnetic field being generated by a current flowing externally to the magnetic element, a storage layer having at least one magnetic easy axis and having a second magnetization that changes direction based on a spin-transfer effect when a write current passes through the magnetic element, and a spacing layer formed between the resettable layer and the storage layer, the method comprising steps of:
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setting the first magnetization of the resettable layer in the selected direction by generating the external magnetic field; and
changing a direction of the second magnetization of the storage layer by passing a write current through the magnetic element, the write current having a magnitude that is greater than or equal to a magnitude of a current that switches the magnetization of the storage layer. - View Dependent Claims (65, 66, 67, 68, 69, 70, 71, 72, 73, 74)
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75. A method for reading a magnetic element, the magnetic element including at least one resettable layer, each resettable layer having a magnetization that is set in a selected direction by at least one magnetic field, each magnetic field being generated by a current flowing externally to the magnetic element, and a storage layer having at least one magnetic easy axis and having a second magnetization that changes direction based on a spin-transfer effect when a write current is passed through the magnetic element, the method comprising steps of:
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setting the magnetization of each resettable layer in a first selected direction by generating at least one external magnetic field;
passing a first current through the magnetic element while the magnetization of each resettable layer is set in the first selected direction;
setting the magnetization of each resettable layer in a second selected direction by generating at least one external magnetic field, the second selected direction being opposite the first selected direction;
passing a second current through the magnetic element while the magnetization of each resettable layer is set in the second selected direction;
detecting a voltage across the magnetic element when each respective read current is passed through the magnetic element; and
determining an information value stored in the magnetic cell based on the detected voltages. - View Dependent Claims (76, 77)
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78. A method for reading a magnetic element, the magnetic element including a resettable layer having a first magnetization that is set in a selected direction by at least one magnetic field, each magnetic field being generated by a current flowing externally to the magnetic element, a storage layer having at least one magnetic easy axis and having a second magnetization that changes direction based on a spin-transfer effect when a write current passes through the magnetic element, a pinned magnetic layer having a third magnetization, an antiferromagnetic layer that pins the third magnetization in a predetermined direction, and a tunneling barrier layer between storage layer and the pinned layer, the method comprising steps of:
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passing a first read current through the magnetic element, the first read current having a magnitude that is less than a magnitude of a current that switches the magnetization of the storage layer;
detecting a first voltage across the magnetic element when the first read current is passed through the magnetic element;
setting the first magnetization of the resettable layer in the selected direction by generating at least one external magnetic field;
passing a write current through the magnetic element, the write current having a magnitude that is greater than or equal to the magnitude of the current that switches the magnetization of the storage layer;
passing a second read current through the magnetic element, the second read current having a magnitude that is less than the magnitude of the current that switches the magnetization of the storage layer;
detecting a second voltage across the magnetic element when the second read current is passed through the magnetic element;
determining an information value stored in the magnetic cell by comparing the first and second detected voltages. - View Dependent Claims (79, 80)
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Specification