Spin Injection and Detection in Spin Valves with Integrated Tunnel Barriers

Abstract

In paramagnetic metals, a nonequilibrium spin polarization injected from a ferromagnetic region can be sustained. We give an overview of various possibilities to realize spin injection in all-metal spin-valve devices consisting of two ferromagnetic electrodes and an interconnecting normal metal strip. Contributions to the local and the nonlocal magnetoresistance of such lateral spin valves are discussed. The strong increase of spin-injection efficiency as a consequence of the incorporation of tunnel barriers into spin valves is understood in the framework of a diffusive theory that includes spin diffusion, spin relaxation, and spin precession.