Patent attributes
First and second tunnel junctions having a common electrode composed of a nonmagnetic conductor and each of which has a counterelectrode composed of a ferromagnet are spaced apart from each other by a distance that is shorter than a spin diffusion length of the nonmagnetic conductor. The first tunnel junction injects spin from the ferromagnet into the nonmagnetic conductor and the second tunnel junction detects, between the ferromagnetic metal and the nonmagnetic conductor, a voltage that accompanies spin injection of the first tunnel junction. The nonmagnetic conductor may be a semiconductor or semimetal that is lower in carrier density than a metal. The common electrode alternatively may be composed of a superconductor. A spin injection device thus provided can exhibit a large signal voltage with a low current and under low magnetic field and can be miniaturized in device size.
