Magnetoresistance effect element

A magnetoresistance effect element comprising:

• a first pinned ferromagnetic layer configured to keep a magnetization direction thereof fixed on application of a magnetic field;
• a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer and configured to keep a magnetization direction thereof fixed on application of the magnetic field;
• a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers and configured to be capable of changing a magnetization direction thereof on application of the magnetic field;
• a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer;
• and
• a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer, the first and second tunnel barrier layers being different from each other in composition.

A magnetic random access memory comprising:

• word lines;
• bit lines intersecting the word lines;
• and memory cells, each memory cell disposed in each of intersection regions of the word lines and the bit lines, wherein each of the memory cells comprises a magnetoresistance effect element, and the magnetoresistance effect element comprises:
• a first pinned ferromagnetic layer configured to keep a magnetization direction thereof fixed on application of a magnetic field;
• a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer and configured to keep a magnetization direction thereof fixed on application of the magnetic field, a surface region of the first pinned ferromagnetic layer and a surface region of the second pinned ferromagnetic layer facing each other being different from each other in composition;
• a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers and configured to be capable of changing a magnetization direction thereof on application of the magnetic field;
• a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer;
• and
• a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer.

A magnetic random access memory comprising:

• word lines;
• bit lines intersecting the word lines;
• and memory cells, each memory cell disposed in each of intersection regions of the word lines and the bit lines, wherein each of the memory cells comprises a magnetoresistance effect element, and the magnetoresistance effect element comprises:
• a first pinned ferromagnetic layer configured to keep a magnetization direction thereof fixed on application of a magnetic field;
• a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer and configured to keep a magnetization direction thereof fixed on application of the magnetic field;
• a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers and configured to be capable of changing a magnetization direction thereof on application of the magnetic field;
• a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer;
• and
• a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer, the first and second tunnel barrier layers being different from each other in composition.

A magnetic head comprising:

• a support member;
• and a magnetoresistance effect element supported by the support member, wherein the magnetoresistance effect element comprises:
• a first pinned ferromagnetic layer configured to keep a magnetization direction thereof fixed on application of a magnetic field;
• a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer and configured to keep a magnetization direction thereof fixed on application of the magnetic field, a surface region of the first pinned ferromagnetic layer and a surface region of the second pinned ferromagnetic layer facing each other being different from each other in composition;
• a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers and configured to be capable of changing a magnetization direction thereof on application of the magnetic field;
• a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer;
• and
• a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer.

A magnetic head comprising:

• a support member;
• and a magnetoresistance effect element supported by the support member, wherein the magnetoresistance effect element comprises:
• a first pinned ferromagnetic layer configured to keep a magnetization direction thereof fixed on application of a magnetic field;
• a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer and configured to keep a magnetization direction thereof fixed on application of the magnetic field;
• a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers and configured to be capable of changing a magnetization direction thereof on application of the magnetic field;
• a first tunnel barrier layer intervening between the first pinned ferromagnetic layer and the free ferromagnetic layer;
• and
• a second tunnel barrier layer intervening between the second pinned ferromagnetic layer and the free ferromagnetic layer, the first and second tunnel barrier layers being different from each other in composition.