Ferromagnetic double tunnel junction element with asymmetric energy band

A magnetic random access memory comprising:

• word lines;
• bit lines intersecting the word lines;
• and
• memory cells each positioned in each of intersection regions of the word lines and the bit lines and each including a magnetoresistance effect element, the magnetoresistance effect element including:
• a first pinned ferromagnetic layer,
• a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer,
• a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers,
• 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,
• wherein the first and second tunnel barrier layers are different from each other in composition.

A magnetic head comprising:

• a support member;
• and
• a magnetoresistance effect element supported by the support member, the magnetoresistance effect element including:
• a first pinned ferromagnetic layer,
• a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer,
• a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers,
• 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,
• wherein the first and second tunnel barrier layers are different from each other in composition.

A magnetoresistance effect element comprising:

• a first pinned ferromagnetic layer;
• a second pinned ferromagnetic layer facing the first pinned ferromagnetic layer;
• a free ferromagnetic layer intervening between the first and second pinned ferromagnetic layers;
• 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,
• wherein the first and second tunnel barrier layers contain at least one material selected from the group consisting of Al2O3, SiO2, MgO, AlN, AlON, GaO, Bi2O3, SrTiO2 and AlLaO3, and the material contained in the first tunnel barrier layer and the material contained in the second tunnel barrier layer are different from each other.

A magnetoresistance effect element comprising:

• a first ferromagnetic layer as a pinned ferromagnetic layer;
• a first tunnel barrier layer formed on the first ferromagnetic layer such that the magnetoresistance effect element exhibits magnetoresistance effect;
• a second ferromagnetic layer as a free ferromagnetic layer formed on the first tunnel barrier layer;
• a second tunnel barrier layer formed on the second ferromagnetic layer such that the magnetoresistance effect element exhibits magnetoresistance effect;
• and
• a third ferromagnetic layer as a pinned ferromagnetic layer formed on the second tunnel barrier layer,
• wherein the second ferromagnetic layer includes a fourth ferromagnetic layer, a nonmagnetic metal layer formed on the fourth ferromagnetic layer, and a fifth ferromagnetic layer formed on the nonmagnetic metal layer, and a material contained in the first tunnel barrier layer and a material contained in the second tunnel barrier layer are different from each other.