Patent ID: 8487359

Claim:
A spin MOSFET comprising: a substrate that has a semiconductor region of a first conductivity type; first and second ferromagnetic stacked films that are formed at a distance from each other on the semiconductor region, and each have the same stacked structure comprising a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer stacked in this order, the second ferromagnetic stacked film having a same or different aspect ratio and a film-plane area at least 1.1 times larger than that of the first ferromagnetic stacked film, the first ferromagnetic layers of the first and second ferromagnetic stacked films having substantially same layer thickness and being made of substantially same material, the nonmagnetic layers of the first and second ferromagnetic stacked films having substantially same layer thickness and being made of substantially same material, the second ferromagnetic layers of the first and second ferromagnetic stacked films having substantially same layer thickness and different from the first ferromagnetic layers of the first and second ferromagnetic stacked films and being made of substantially the same material, the first ferromagnetic layers of the first and second ferromagnetic stacked films being closest to the substrate among the first and second ferromagnetic stacked films; a gate insulating film that is formed on a portion of the semiconductor region, the portion being located between the first ferromagnetic stacked film and the second ferromagnetic stacked film; and a gate that is formed on the gate insulating film, wherein the portion of the semiconductor region is a current path of each of writing current and reading current, the first ferromagnetic layer in the first ferromagnetic stacked film has a magnetization that is changeable and the second ferromagnetic layer in the first ferromagnetic stacked film has a magnetization that is unchangeable when the writing current is flowed between the first and second ferromagnetic stacked films via the portion of the semiconductor region, and each of the first and second ferromagnetic layers in the second ferromagnetic stacked film has a magnetization that is unchangeable when the writing current is flowed between the first and second ferromagnetic stacked films via the portion of the semiconductor region.