Giant spin-accumulation signal and pure spin-current-induced reversible magnetization switching

A number of proposed next-generation electronic devices, including novel memory elements(1) and versatile transistor circuits(2), rely on spin currents, that is, the flow of electron angular momentum. A spin current may interact with a magnetic nanostructure and give rise to spin-dependent transport phenomena, or excite magnetization dynamics(1-11). In contrast to a spin-polarized charge current, a pure spin current does not produce any charge-related spurious effects(12,13). One way to produce a pure spin current is non-local electrical-spin injection(12-18), but this approach has suffered so far from low injection efficiency. Here, we demonstrate a significant enhancement of the non-local injection efficiency in a lateral spin valve prepared with an entirely in situ fabrication process. Improvements to the interface quality and the device structure lead to an increase of the spin-signal amplitude by an order of magnitude. The generated pure spin current enables the magnetization reversal of a nanomagnet with the same efficiency as in the case of using charge currents. These results are important for further theoretical developments in multi-terminal structures(2), but also with a view towards realizing novel devices driven by pure spin currents.