Spin transistor, integrated circuit, and magnetic memory

A spin transistor comprising:

• a first ferromagnetic layer;
• a second ferromagnetic layer;
• a semiconductor layer between the first and second ferromagnetic layers;
• and
• a gate electrode on or above a surface of the semiconductor layer, the surface being between the first and second ferromagnetic layers,
• wherein one of the first and second ferromagnetic layers has an invariable magnetization and the other has a variable magnetization,
• wherein data are stored by a relation of magnetization directions of the first and second ferromagnetic layers,
• wherein electrons flow from the first ferromagnetic layer to the second ferromagnetic layer in a read operation, and
• wherein the second ferromagnetic layer comprises a ferromagnet which has a first minority spin band located at a high energy side and a second minority spin band located at a low energy side, and has a Fermi level in an area of the low energy side lower than a middle of a gap between the first and second minority spin bands.

A spin transistor comprising:

• a first ferromagnetic layer;
• a second ferromagnetic layer;
• a semiconductor layer between the first and second ferromagnetic layers;
• and
• a gate electrode on or above a surface of the semiconductor layer, the surface being between the first and second ferromagnetic layers,
• wherein one of the first and second ferromagnetic layers has an invariable magnetization and the other has a variable magnetization,
• wherein data are stored by a relation of magnetization directions of the first and second ferromagnetic layers,
• wherein electrons flow from the first ferromagnetic layer to the second ferromagnetic layer in a read operation, and
• wherein the first ferromagnetic layer comprises a ferromagnet which has a first minority spin band located at a high energy side and a second minority spin band located at a low energy side, and has a Fermi level in an area of the high energy side higher than a middle of a gap between the first and second minority spin bands, and
• the second ferromagnetic layer comprises a ferromagnet which has a third minority spin band located at a high energy side and a fourth minority spin band located at a low energy side, and has a Fermi level in an area of the low energy side lower than a middle of a gap between the third and fourth minority spin bands.