Magneto-transport in a two-dimensional electron gas spin valve

Spin injection from ferromagnetic leads with different coercivity fields via tunnel barrier into 2-dimensional electron gas (2DEG) is studied. When the magnetizations of the two leads are in misalignment configuration, the current between the two-leads at a fixed bias voltage is suppressed. Judging from the amount of the suppression, we conclude that the spin injection efficiency is greater than 68%, and the spin relaxation length is longer than 1.4 µm. Hybrid ferromagnet-semiconductor devices have potential applications in spin field-effect-transistors (spin-FETs) in which the period of spin precession is controlled by the gate-induced field. This device utilizes the Rashba effect in which the crystal electric field serves as the effective magnetic field acting on the spin-orbit interaction and induces carrier spin precession in the conduction channel. To make the spin precession effective, a semiconductor with strong spin-orbit coupling is desirable, and a common choice would be the GaAs 2DEG system.