SPIN-INJECTION DEVICE AND MAGNETIC DEVICE USING SPIN-INJECTION DEVICE

摘要

A first tunnel junction (2) is composed of a common electrode of a nonmagnetic conductor (4) and an electrode of a ferromagnetic body (6), and a second tunnel junction (3) is composed of the common electrode and an electrode of a ferromagnetic body (8). The first and second tunnel junctions (2, 3) are spaced at an interval shorter than the spin-diffusion length of the nonmagnetic conductor (4). In the first tunnel junction (2), spins are injected from the ferromagnetic metal (6) to the nonmagnetic conductor (4); in the second tunnel junction (3), the voltage developed by the spin injection in the first tunnel junction (2) is detected by means of the ferromagnetic metal (8) and the nonmagnetic conductor (4). The carrier density of the nonmagnetic conductor (4) is lower than those of metals. The nonmagnetic conductor (4) is a semiconductor or a semimetal. The common electrode can be a superconductor (4'). Thus a high signal voltage can be produced even with a small current and even in a weak magnetic field, and a miniaturizable spin-injection device and a magnetic device comprising such a spin-injection device are provided.