Magneto-resistance effect element magneto-resistance effect memory cell, MRAM, and method for performing information write to or read from the magneto-resistance effect memory cell

A magneto-resistive effect element, comprising:

• a first ferromagnetic film;
• a second ferromagnetic film;
• and
• a first nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film,
• wherein:
• the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film by an external magnetic field, and
• the first ferromagnetic film includes:
• a second nonmagnetic film,
• a third ferromagnetic film, and
• a fourth ferromagnetic film,
• wherein the third ferromagnetic film and the fourth ferromagnetic film are antiferromagnetically exchange-coupled with each other through the second nonmagnetic film.

A magneto-resistive effect memory cell, comprising:

• a first ferromagnetic film;
• a second ferromagnetic film;
• a first nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film;
• and
• at least one conductive film for causing a magnetization rotation of at least the first ferromagnetic film,
• wherein:
• the first ferromagnetic film has a magnetization more easily rotatable the a magnetization of the second ferromagnetic film by an external magnetic field, and
• the first ferromagnetic film includes:
• an amorphous magnetic film, and
• a third nonmagnetic film in contact with the first nonmagnetic film and interposed between the amorphous film and the first nonmagnetic film.

A magneto-resistive effect memory cell, comprising:

• a first ferromagnetic film;
• a second ferromagnetic film;
• a first nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film;
• and
• at least one conductive film for causing a magnetization rotation of at least the first ferromagnetic film,
• wherein
• the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film by an external magnetic field, and
• the first ferromagnetic film includes:
• a second nonmagnetic film,
• a third ferromagnetic film, and
• a fourth ferromagnetic fibs,
• wherein the third ferromagnetic film and the fourth ferromagnetic film are antiferromagnetically exchange-coupled with each other through the second nonmagnetic film.

A method for writing information to and reading information from a magneto-resistive effect memory cell, the magneto-resistive effect memory cell including:

• a first ferromagnetic film,
• a second ferromagnetic film,
• a nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, end at least one conductive film,
• wherein the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film by en external magnetic field,
• the method comprising the steps of:
• causing a first current to flow in the at least one conductive film to cause a magnetization rotation of at least the first ferromagnetic film, thereby writing information in the magneto-resistive effect memory cell;
• and
• causing a second current to flow in the first ferromagnetic film, the nonmagnetic film, and the second ferromagnetic film;
• and causing a third current, which is a combination of a positive bias current and a negative bias current, to flow in the at least one conductive film, thereby reading a voltage value corresponding to the second current and thus reading information written in the magneto-resistive element memory call.

A method for writing information to and reading information from an MRAM including a plurality of magneto-resistive effect memory cells, each magneto-resistive effect memory cell including:

• a first ferromagnetic film,
• a second ferromagnetic film,
• a nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, and at least one conductive film,
• wherein the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film by an external magnetic field,
• the plurality of conductive films being arranged in at least one prescribed direction, the method comprising the steps of:
• causing a first current to flow in the at least one conductive film of a first magneto-resistive effect memory cell of the plurality of magneto-resistive effect memory cells to cause a magnetization rotation of at least the first ferromagnetic film of the first magneto-resistive effect memory cell, thereby writing information in the first magneto-resistive effect memory cell;
• and
• causing a second current to flow in the first ferromagnetic film, the nonmagnetic film, and the second ferromagnetic film of the first magneto-resistive effect memory cell;
• and causing a third current, which is a combination of a positive bias current and a negative bias current, to flow in the at least one conductive film of the first magneto-resistive effect memory cell, thereby reading a voltage value corresponding to the second current and thus reading information written in the first magneto-resistive effect memory cell.

A method for reading information from a magneto-resistive effect memory cell, the magneto-resistive effect memory cell including:

• a first ferromagnetic film,
• a second ferromagnetic film,
• a nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, and
• at least one conductive film,
• wherein the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film by an external magnetic field,
• the method comprising the step of:
• causing a first current to flow in the first ferromagnetic film, the nonmagnetic film, and the second ferromagnetic film;
• and causing a second current, which is a combination of a positive bias current and a negative bias current, to flow in the at least one conductive film, thereby reading a voltage value corresponding to the first current and thus reading information written in the magneto-resistive effect memory cell.

A method for reading information from an MRAM including a plurality of magneto-resistive effect memory cells, each magneto-resistive effect memory cell including:

• a first ferromagnetic film,
• a second ferromagnetic film,
• a nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, and
• at least one conductive film,
• wherein the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film by an external magnetic field,
• the plurality of conductive films being arranged in at least one prescribed direction, the method comprising the step of:
• causing a first current to flow in the first ferromagnetic film, the nonmagnetic film, and the second ferromagnetic film of a first magneto-resistive effect memory cell of the plurality of magneto-resistive effect memory cells;
• and causing a second current, which is a combination of a positive bias current and a negative bias current, to flow in the at least one conductive film of the first magneto-resistive effect memory cell, thereby reading a voltage value corresponding to the first current and thus reading information written in the first magneto-resistive effect memory cell.

A method for writing multiple levels of a signal to and reading multiple levels of a signal from a magneto-resistive effect memory cell, the magneto-resistive effect memory cell including:

• at least two layer structures;
• at least one first nonmagnetic film interposed between the at least two layer structures;
• and
• at least one conductive film,
• wherein:
• each of the at least two layer structures includes a first ferromagnetic film, a second ferromagnetic film, and a second nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, and
• the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film,
• the method comprising the steps of:
• causing a first current in the at least one conductive film to cause a magnetization rotation of at least one of the first ferromagnetic film and the second ferromagnetic film of each of the at least two layer structures, or to cause a magnetization rotation of none of the first ferromagnetic film and the second ferromagnetic film of each of the at least two layer structures, thereby writing multiple levels of a signal in the magneto-resistive effect memory cell;
• and
• causing a second current to each of the at least two layer structures to compare a resistance value corresponding to the second current and a reference resistance value, thereby reading the multiple levels of the signal written in the magneto-resistive effect memory cell.

A method for writing multiple levels of a signal to a magneto-resistive effect memory cell, the magneto-resistive effect memory cell including:

• at least two layer structures;
• at least one first nonmagnetic film interposed between the at least two layer structures;
• and
• at least one conductive film,
• wherein:
• each of the at least two layer structures includes a first ferromagnetic film, a second ferromagnetic film, and a second nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, and
• the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film,
• the method comprising the steps of:
• causing a first current to flow in the at least one conductive film to cause a magnetization rotation of at least one of the first ferromagnetic film and the second ferromagnetic film of each of the at least two layer structures, or to cause a magnetization rotation of none of the first ferromagnetic film and the second ferromagnetic film of each of the at least two layer structures, thereby writing multiple levels of a signal in the magneto-resistive effect memory cell.

A method for reading multiple levels of a signal from a magneto-resistive effect memory cell, the magneto-resistive effect memory cell including:

• at least two layer structures;
• at least one first nonmagnetic film interposed between the at least two layer structures;
• and
• at least one conductive film,
• wherein:
• each of the at least two layer structures includes a first ferromagnetic film, a second ferromagnetic film, and a second nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, and
• the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film,
• the method comprising the steps of:
• causing a first current to flow in each of the at least two layer structures to compare a resistance value corresponding to the first current and a reference resistance value, thereby reading multiple levels of a signal written in the magneto-resistive effect memory cell.

A method for writing multiple levels of a signal to and reading multiple levels of a signal from an MRAM including a plurality of magneto-resistive effect memory cells, each magneto-resistive effect memory cell, including:

• at least two layer structures;
• at least one first nonmagnetic film interposed between the at least two layer structures;
• and
• at least one conductive film,
• wherein:
• each of the at least two layer structures includes a first ferromagnetic film, a second ferromagnetic film, and a second nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, and
• the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film,
• the plurality of conductive films being arranged in at least one prescribed direction, the method comprising the steps of:
• causing a first current to flow in the at least one conductive film of a first magneto-resistive effect memory cell of the plurality of magneto-resistive effect memory cells to cause a magnetization rotation of at least one of the first ferromagnetic film and the second ferromagnetic film of each of the at least two layer structures of the first magneto-resistive effect memory cell, or to cause a magnetization rotation of none of the first ferromagnetic film and the second ferromagnetic film of each of the at least two layer structures of the first magneto-resistive effect memory cell, thereby writing multiple levels of a signal in the first magneto-resistive effect memory cell;
• and
• causing a second current to flow in each of the at least two layer structures of the first magneto-resistive effect memory cell to compare a resistance value corresponding to the second current and a reference resistance value, thereby reading the multiple levels of the signal written in the first magneto-resistive effect memory cell.

A method for writing multiple levels of a signal in an MRAM including a plurality of magneto-resistive effect memory cells, each magneto-resistive effect memory cell including:

• at least two layer structures;
• at least one first nonmagnetic film interposed between the at least two layer structures;
• and
• at least one conductive film,
• wherein:
• each of the at least two layer structures includes a first ferromagnetic film, a second ferromagnetic film, and a second nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, and
• the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film,
• the plurality of conductive films being arranged in at least one prescribed direction, the method comprising the steps of:
• causing a first current of flow in the at least one conductive film of a first magneto-resistive effect memory cell of the plurality of magneto-resistive effect memory cells to cause a magnetization rotation of at least one of the first ferromagnetic film and the second ferromagnetic film of each of the at least two layer structures of the first magneto-resistive effect memory cell, or to cause a magnetization rotation of none of the first ferromagnetic film and the second ferromagnetic film of each of the at least two layer structures of the first magneto-resistive effect memory cell, thereby writing multiple levels of a signal in the first magneto-resistive effect memory cell.

A method for reading multiple levels of a signal from an MRAM including a plurality of magneto-resistive effect memory cells, each magneto-resistive effect memory cell including:

• at least two layer structures;
• at least one first nonmagnetic film interposed between the at least two layer structures;
• and
• at least one conductive film,
• wherein:
• each of the at least two layer structures includes a first ferromagnetic film, a second ferromagnetic film, and a second nonmagnetic film interposed between the first ferromagnetic film and the second ferromagnetic film, and
• the first ferromagnetic film has a magnetization more easily rotatable than a magnetization of the second ferromagnetic film,
• the plurality of conductive films being arranged in at least one prescribed direction, the method comprising the steps of:
• causing a first current to flow in each of the at least two layer structures of a first magneto-resistive effect memory cell of the plurality of magneto-resistive effect memory cells to compare a resistance value corresponding to a the first current and a reference resistance value, thereby reading multiple levels of a signal written in the first magneto-resistive effect memory cell.