Electrical spin injection and accumulation at room temperature in an all-metal mesoscopic spin valve

Finding a means to generate, control and use spin-polarized currents repres ents an important challenge for spin-based electronics(1-3), or 'spintronic s'. Spin currents and the associated phenomenon of spin accumulation can be realized by driving a current from a ferromagnetic electrode into a non-ma gnetic metal or semiconductor. This was first demonstrated over 15 years ag o in a spin injection experiment(4) on a single crystal aluminium bar at te mperatures below 77 K. Recent experiments(5-8) have demonstrated successful optical detection of spin injection in semiconductors, using either optica l injection by circularly polarized light or electrical injection from a ma gnetic semiconductor. However, it has not been possible to achieve fully el ectrical spin injection and detection at room temperature. Here we report r oom-temperature electrical injection and detection of spin currents and obs erve spin accumulation in an all-metal lateral mesoscopic spin valve, where ferromagnetic electrodes are used to drive a spin-polarized current into c rossed copper strips. We anticipate that larger signals should be obtainabl e by optimizing the choice of materials and device geometry.