Nonvolatile magnetoresistive memory with fully closed flux operation

Claim 2

A memory cell comprising a storage element having a first structure, the first structure having a plurality of layers, selected layers having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the storage element has a closed flux structure in at least one dimension, and wherein the magnetization vectors are substantially confined to the at least one dimension during all stages of operation of the storage element.

Claim 3

The memory cell of claim 1 wherein the plurality of layers comprises a first number of ferromagnetic layers alternating with a second number of nonmagnetic conducting layers, the second number being at least one less than the first number, the magnetization vectors being associated with the ferromagnetic layers.

Claim 4

The memory cell of claim 2 wherein the first number of ferromagnetic layers comprises at least a first layer having a first coercivity and at least a second layer having a second coercivity, the second coercivity being greater than the first coercivity.

Claim 5

The memory cell of claim 3 wherein at least one second layer is in contact with an oxide layer, thereby raising a switching threshold of the at least one second layer.

Claim 6

The memory cell of claim 1 wherein a first layer of the storage element is for storage of information and a second layer of the storage element is for nondestructive readout of the information.

Claim 7

The memory cell of claim 1 wherein the first structure comprises a plurality of legs, one of the legs being a multilayer structure exhibiting giant magnetoresistance, each magnetic layer of the multilayer structure having a square-loop structure.

Claim 8

The memory cell of claim 1 wherein the first structure comprises a multilayer toroidal structure exhibiting giant magnetoresistance.

Claim 9

The memory cell of claim 1 further comprising: means for reading information from and writing information to the first structure; and a selection conductor for applying a selection signal to the storage element to enable reading from and writing to the first structure.

Claim 10

The memory cell of claim 8 wherein the reading and writing means comprise a read conductor electrically coupled to the first structure, and a write conductor electrically isolated from the read conductor and the first structure.

Claim 11

The memory cell of claim 8 wherein the reading and writing means comprise a single conductor electrically coupled to the first structure.

Claim 12

The memory cell of claim 8 wherein the reading and writing means comprise a digit line, and the selection conductor comprises a word line, information being stored in the first structure in a region where the word line is parallel to the digit line.

Claim 15

The array of claim 12 wherein the plurality of layers in each storage element comprises a first number of ferromagnetic layers alternating with a second number of nonmagnetic conducting layers, the second number being at least one less than the first number, the magnetization vectors being associated with the ferromagnetic layers.

Claim 16

The array of claim 13 wherein the first number of ferromagnetic layers comprises at least a first layer having a first coercivity and at least a second layer having a second coercivity, the second coercivity being greater than the first coercivity.

Claim 17

The array of claim 14 wherein at least one second layer is in contact with an oxide layer, thereby raising a switching threshold of the at least one second layer.

Claim 18

The array of claim 12 wherein for each storage element, a first layer is for storage of information and a second layer is for nondestructive readout of the information.

Claim 19

The array of claim 12 wherein the first structure of each storage element comprises a square-loop structure having a plurality of legs, one of the legs being a multilayer structure exhibiting giant magnetoresistance.

Claim 20

The array of claim 12 wherein the first structure of each storage element comprises a multilayer toroidal structure exhibiting giant magnetoresistance.

Claim 21

The array of claim 12 wherein the plurality of read and write conductors comprises a plurality of read conductors and a plurality of write conductors, wherein each row of storage elements has a read conductor and a write conductor associated therewith, the read conductor of a particular row being electrically coupled to the first structures of the storage elements in the particular row, and the write conductor associated with the particular row being electrically isolated from the first structures of the storage elements in the particular row and from the read conductor associated with the particular row.

Claim 22

The array of claim 12 wherein the plurality of read and write conductors comprises a plurality of dual-purpose read/write conductors, wherein each row of storage elements has a read/write conductor associated therewith, the read/write conductor of a particular row being electrically coupled to the first structures of the storage elements in the particular row.

Claim 23

The array of claim 12 further comprising support electronics wherein the support electronics are all-metal devices.

Claim 24

The array of claim 21 wherein the support electronics comprise a plurality of giant magnetoresistive all-metal spin transistors.

Claim 27

The method of claim 23 wherein the step of applying a select signal comprises changing the orientation of the at least a first magnetization vector a plurality of times, the orientation of the at least a first magnetization vector oscillating between being parallel and antiparallel to the at least a second magnetization vector.

Claim 30

A thin-film memory cell, comprising: a multilayer thin-film storage element exhibiting giant magnetoresistance, the storage element having a top, a bottom, an aperture therethrough, and a magnetization around the aperture; a thin-film word line passing through the aperture, the thin-film word line being electrically isolated from the thin-film storage element; and a segmented thin-film sense/digit line having two segments coupled to the thin-film storage element such that current flowing through the thin-film sense/digit line passes through the thin-film storage element, the sense/digit line exhibiting a resistance which depends on orientations of magnetization vectors in the multilayer thin-film storage element; wherein the magnetization in the thin-film storage element is switched from a clockwise direction around the aperture to a counterclockwise direction around the aperture and from a counterclockwise direction around the aperture to a clockwise direction around the aperture in response to a coincidence of current in the segmented sense/digit line and the word line, the magnetization of the thin-film storage element having a closed flux orientation during substantially all stages of operation of the thin-film storage element.

Claim 31

A thin-film memory cell, comprising: a multilayer thin-film storage element exhibiting giant magnetoresistance, the storage element having a top, a bottom, an aperture therethrough, and a magnetization around the aperture; a thin-film word line passing through the aperture, the thin-film word line being electrically isolated from the thin-film storage element; and a segmented thin-film sense/digit line having two segments coupled to the thin-film storage element such that current flowing through the thin-film sense/digit line passes through the thin-film storage element, the sense/digit line exhibiting a resistance which depends on orientations of magnetization vectors in the multilayer thin-film storage element; wherein the magnetization in the thin-film storage element is switched from a clockwise direction around the aperture to a counterclockwise direction around the aperture and from a counterclockwise direction around the aperture to a clockwise direction around the aperture in response to a coincidence of current in the segmented sense/digit line and the word line, the magnetization of the thin-film storage element having a closed flux orientation during substantially all stages of operation of the thin-film storage element.

Claim 32

The thin-film memory cell of claim 26 wherein the thin-film storage element is a multilayer film comprising low-coercivity magnetic layers separated from high-coercivity magnetic layers by non-magnetic conducting layers.

Claim 33

A thin-film memory cell, comprising: a multilayer thin-film storage element exhibiting giant magnetoresistance, the storage element having an aperture therethrough, and a magnetization around the aperture; a thin-film word line passing through the aperture, the thin-film word line being electrically isolated from the thin-film storage element; a thin-film digit line passing through the aperture, the thin-film digit line being electrically isolated from the thin-film storage element; and a segmented thin-film sense line having two segments coupled to the thin-film storage element such that current flowing through the thin-film sense line passes through the thin-film storage element, the sense line exhibiting a resistance which depends on orientations of magnetization vectors in the multilayer thin-film storage element; wherein the magnetization in the thin-film storage element is switched from a clockwise direction around the aperture to a counterclockwise direction around the aperture and from a counterclockwise direction around the aperture to a clockwise direction around the aperture in response to a coincidence of current in the digit line and the word line, the magnetization of the thin-film storage element having a closed flux orientation during substantially all stages of operation of the thin-film storage element.

Claim 34

A thin-film memory cell, comprising: a multilayer thin-film storage element exhibiting giant magnetoresistance, the storage element having an aperture therethrough, and a magnetization around the aperture; a thin-film word line passing through the aperture, the thin-film word line being electrically isolated from the thin-film storage element; a thin-film digit line passing through the aperture, the thin-film digit line being electrically isolated from the thin-film storage element; and a segmented thin-film sense line having two segments coupled to the thin-film storage element such that current flowing through the thin-film sense line passes through the thin-film storage element, the sense line exhibiting a resistance which depends on orientations of magnetization vectors in the multilayer thin-film storage element; wherein the magnetization in the thin-film storage element is switched from a clockwise direction around the aperture to a counterclockwise direction around the aperture and from a counterclockwise direction around the aperture to a clockwise direction around the aperture in response to a coincidence of current in the digit line and the word line, the magnetization of the thin-film storage element having a closed flux orientation during substantially all stages of operation of the thin-film storage element.

Claim 35

A thin-film memory cell, comprising: a multilayer thin-film storage element exhibiting giant magnetoresistance; a thin-film word line deposited on top of the thin-film storage element and electrically isolated therefrom; a serpentine thin-film digit line deposited on top of the thin-film word line and parallel to the thin-film word line in an area over the thin-film storage element, the thin-film digit line being electrically isolated from both the thin-film storage element and the thin-film word line; a keeper element of magnetic material deposited on top of the thin-film storage element, the thin-film word line, and the thin-film digit line, the keeper element being electrically isolated from the thin-film word line and the thin-film digit line; and a segmented thin-film sense line having two segments coupled to the thin-film storage element such that current flowing through the thin-film sense line passes through the thin-film storage element, the sense line exhibiting a resistance which depends on orientations of magnetization vectors in the multilayer thin-film storage element; wherein the magnetization in the thin-film storage element is switched from a clockwise direction around the word and digit lines to a counterclockwise direction around the word and digit lines and from a counterclockwise direction around the word and digit lines to a clockwise direction around the word and digit lines in response to a coincidence of current in the digit line and the word line, the magnetization of the thin-film storage element having a closed flux orientation during substantially all stages of operation of the thin-film storage element.

Claim 36

A thin-film memory cell, comprising: a multilayer thin-film storage element exhibiting giant magnetoresistance; a thin-film word line deposited on top of the thin-film storage element and electrically isolated therefrom; a serpentine thin-film digit line deposited on top of the thin-film word line and parallel to the thin-film word line in an area over the thin-film storage element, the thin-film digit line being electrically isolated from both the thin-film storage element and the thin-film word line; a keeper element of magnetic material deposited on top of the thin-film storage element, the thin-film word line, and the thin-film digit line, the keeper element being electrically isolated from the thin-film word line and the thin-film digit line; and a segmented thin-film sense line having two segments coupled to the thin-film storage element such that current flowing through the thin-film sense line passes through the thin-film storage element, the sense line exhibiting a resistance which depends on orientations of magnetization vectors in the multilayer thin-film storage element; wherein the magnetization in the thin-film storage element is switched from a clockwise direction around the word and digit lines to a counterclockwise direction around the word and digit lines and from a counterclockwise direction around the word and digit lines to a clockwise direction around the word and digit lines in response to a coincidence of current in the digit line and the word line, the magnetization of the thin-film storage element having a closed flux orientation during substantially all stages of operation of the thin-film storage element.

Claim 37

The thin-film memory cell of claim 29 wherein the thin-film storage element and the keeper element each comprise a multilayer structure exhibiting giant magnetoresistance, the keeper element being electrically coupled to the thin-film storage element.

Claim 38

The thin-film memory cell of claim 29 wherein the thin-film digit line is electrically coupled to the thin-film sense line thereby forming a dual purpose digit-sense line.

Claim 39

A storage element comprising a first structure having a plurality of layers, selected layers having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the storage element has a closed flux structure in at least one dimension, and wherein the magnetization vectors are substantially confined to the at least one dimension during all stages of operation of the storage element.

Claim 40

A storage element comprising a first structure having a plurality of layers, selected layers having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the storage element has a closed flux structure in at least one dimension, and wherein the magnetization vectors are substantially confined to the at least one dimension during all stages of operation of the storage element.

Claim 41

A memory cell comprising a magnetic storage element having at least one magnetization vector associated therewith, and a sensing element having a first structure, the first structure having a plurality of layers, selected layers also having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the memory cell has a closed flux structure in at least one dimension, and wherein the magnetization vectors of the magnetic storage element and the sensing element are substantially confined to the at least one dimension during all stages of operation of the memory cell.

Claim 42

A memory cell comprising a magnetic storage element having at least one magnetization vector associated therewith, and a sensing element having a first structure, the first structure having a plurality of layers, selected layers also having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the memory cell has a closed flux structure in at least one dimension, and wherein the magnetization vectors of the magnetic storage element and the sensing element are substantially confined to the at least one dimension during all stages of operation of the memory cell.

Claim 43

The memory cell of claim 33 further comprising a word line, and a digit line, the word and digit lines being parallel in an area adjacent the magnetic storage element.

Claim 44

A thin-film memory cell comprising: a multilayer thin-film storage element exhibiting giant magnetoresistance, the storage element being characterized by a magnetization, and having a region associated therewith; a thin-film sense line electrically connected to the storage element such that current in the sense line flows through the storage element; a thin-film digit line; and a thin-film word line electrically isolated from the storage element and the digit line, the word line being oriented substantially parallel to the digit line in the region of the storage element; wherein the magnetization in the storage element is switched from a clockwise direction around the word and digit lines to a counterclockwise direction and from the counterclockwise direction around the word and digit lines to the clockwise direction in response to a coincidence of current in the word and digit lines, the magnetization being confined to a closed flux structure during all stages of operation of the memory cell.

Claim 45

A thin-film memory cell comprising: a multilayer thin-film storage element exhibiting giant magnetoresistance, the storage element being characterized by a magnetization, and having a region associated therewith; a thin-film sense line electrically connected to the storage element such that current in the sense line flows through the storage element; a thin-film digit line; and a thin-film word line electrically isolated from the storage element and the digit line, the word line being oriented substantially parallel to the digit line in the region of the storage element; wherein the magnetization in the storage element is switched from a clockwise direction around the word and digit lines to a counterclockwise direction and from the counterclockwise direction around the word and digit lines to the clockwise direction in response to a coincidence of current in the word and digit lines, the magnetization being confined to a closed flux structure during all stages of operation of the memory cell.

Claim 46

The thin-film memory cell of claim 35 wherein the digit line is in electrical contact with the sense line thereby forming a dual purpose sense/digit line.

Claim 47

The thin-film memory cell of claim 35 further comprising a deposited keeper element comprising a multilayer structure exhibiting giant magnetoresistance.

Claim 48

The thin-film memory cell of claim 35 further comprising a deposited keeper element electrically coupled to the word line thereby forming a dual-purpose keeper/word line.

Claim 49

The thin-film memory cell of claim 35 further comprising a deposited keeper element electrically coupled to the multilayer storage element and electrically isolated from the word line.

Claim 50

The thin-film memory cell of claim 35 further comprising a deposited keeper element, wherein the digit line and the word line are sandwiched between the multilayer storage element and the keeper element.

Claim 51

A memory cell comprising a storage element having a first structure, the first structure having a plurality of layers, selected layers having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the storage element has a closed flux structure in at least one dimension, and wherein upon application of a half-select current the magnetization vectors of the storage element are substantially confined to the at least one dimension.

Claim 52

A memory cell comprising a storage element having a first structure, the first structure having a plurality of layers, selected layers having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the storage element has a closed flux structure in at least one dimension, and wherein upon application of a half-select current the magnetization vectors of the storage element are substantially confined to the at least one dimension.

Claim 53

The memory cell of claim 41 wherein the plurality of layers comprises a first number of ferromagnetic layers alternating with a second number of nonmagnetic conducting layers, the second number being at least one less than the first number, the magnetization vectors being associated with the ferromagnetic layers.

Claim 54

The memory cell of claim 42 wherein the first number of ferromagnetic layers comprises at least a first layer having a first coercivity and at least a second layer having a second coercivity, the second coercivity being greater than the first coercivity.

Claim 55

The memory cell of claim 43 wherein at least one second layer is in contact with an oxide layer, thereby raising a switching threshold of the at least one second layer.

Claim 56

The memory cell of claim 41 wherein a first layer of the storage element is for storage of information and a second layer of the storage element is for nondestructive readout of the information.

Claim 57

The memory cell of claim 41 wherein the first structure comprises a plurality of legs, one of the legs being a multilayer structure exhibiting giant magnetoresistance, each magnetic layer of the multilayer structure having a square-loop structure.

Claim 58

The memory cell of claim 41 wherein the first structure comprises a multilayer toroidal structure exhibiting giant magnetoresistance.

Claim 59

The memory cell of claim 41 further comprising: means for reading information from and writing information to the first structure; and a selection conductor for applying a selection signal to the storage element to enable reading from and writing to the first structure.

Claim 60

The memory cell of claim 48 wherein the reading and writing means comprise a read conductor electrically coupled to the first structure, and a write conductor electrically isolated from the read conductor and the first structure.

Claim 61

The memory cell of claim 48 wherein the reading and writing means comprise a single conductor electrically coupled to the first structure.

Claim 62

The memory cell of claim 48 wherein the reading and writing means comprise a digit line, and the selection conductor comprises a word line, information being stored in the first structure in a region where the word line is parallel to the digit line.

Claim 65

The array of claim 52 wherein the plurality of layers in each storage element comprises a first number of ferromagnetic layers alternating with a second number of nonmagnetic conducting layers, the second number being at least one less than the first number, the magnetization vectors being associated with the ferromagnetic layers.

Claim 66

The array of claim 53 wherein the first number of ferromagnetic layers comprises at least a first layer having a first coercivity and at least a second layer having a second coercivity, the second coercivity being greater than the first coercivity.

Claim 67

The array of claim 54 wherein at least one second layer is in contact with an oxide layer, thereby raising a switching threshold of the at least one second layer.

Claim 68

The array of claim 52 wherein for each storage element, a first layer is for storage of information and a second layer is for nondestructive readout of the information.

Claim 69

The array of claim 52 wherein the first structure of each storage element comprises a square-loop structure having a plurality of legs, one of the legs being a multilayer structure exhibiting giant magnetoresistance.

Claim 70

The array of claim 52 wherein the first structure of each storage element comprises a multilayer toroidal structure exhibiting giant magnetoresistance.

Claim 71

The array of claim 52 wherein the plurality of read and write conductors comprises a plurality of read conductors and a plurality of write conductors, wherein each row of storage elements has a read conductor and a write conductor associated therewith, the read conductor of a particular row being electrically coupled to the first structures of the storage elements in the particular row, and the write conductor associated with the particular row being electrically isolated from the first structures of the storage elements in the particular row and from the read conductor associated with the particular row.

Claim 72

The array of claim 52 wherein the plurality of read and write conductors comprises a plurality of dual-purpose read/write conductors, wherein each row of storage elements has a read/write conductor associated therewith, the read/write conductor of a particular row being electrically coupled to the first structures of the storage elements in the particular row.

Claim 73

The array of claim 52 further comprising support electronics wherein the support electronics are all-metal devices.

Claim 74

The array of claim 61 wherein the support electronics comprise a plurality of giant magnetoresistive all-metal spin transistors.

Claim 77

The method of claim 63 wherein the step of applying a select signal comprises changing the orientation of the at least a first magnetization vector a plurality of times, the orientation of the at least a first magnetization vector oscillating between being parallel and antiparallel to the at least a second magnetization vector.

Claim 80

A storage element comprising a first structure having a plurality of layers, selected layers having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the storage element has a closed flux structure in at least one dimension, and wherein upon application of a half-select current the magnetization vectors are substantially confined to the at least one dimension.

Claim 81

A storage element comprising a first structure having a plurality of layers, selected layers having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the storage element has a closed flux structure in at least one dimension, and wherein upon application of a half-select current the magnetization vectors are substantially confined to the at least one dimension.

Claim 82

A memory cell comprising a magnetic storage element having at least one magnetization vector associated therewith, and a sensing element having a first structure, the first structure having a plurality of layers, selected layers also having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the memory cell has a closed flux structure in at least one dimension, and wherein upon application of a half-select current the magnetization vectors of the magnetic storage element and the sensing element are substantially confined to the at least one dimension.

Claim 83

A memory cell comprising a magnetic storage element having at least one magnetization vector associated therewith, and a sensing element having a first structure, the first structure having a plurality of layers, selected layers also having magnetization vectors associated therewith, the first structure exhibiting giant magnetoresistance, wherein the memory cell has a closed flux structure in at least one dimension, and wherein upon application of a half-select current the magnetization vectors of the magnetic storage element and the sensing element are substantially confined to the at least one dimension.

Claim 84

The memory cell of claim 67 further comprising a word line, and a digit line, the word and digit lines being parallel in an area adjacent the magnetic storage element.