Non-local spin injection in lateral spin valves

Injection and detection of non-local spin accumulation have been demonstrated in a series of nanoscale metallic lateral spin valves, fabricated by electron beam lithography. A distinct feature of non-local spin valves is that a pure spin current without charge flow can be generated. The measured spin signal is only sensitive to the relative orientations of the detector spin and the spin accumulation, and exhibits little charge background voltage. The injection polarizations of the interfaces and the spin diffusion lengths of the non-magnetic components have been determined by measuring the spin signals from a set of similar spin valves with varying injector and detector separations. In Py/Au/Py lateral spin valves, where Py is permalloy, the injection polarization across the Py/Au interface is 3%, and the spin diffusion length of Au is 63 +/- 15 nm at 10 K. In Co/Cu/Co lateral spin valves, the injection polarization across the Co/Cu interface is increased to over 7%, due to better interfacial quality compared with Py/Au. The spin diffusion length of Cu is 200 +/- 20 nm at 10 K, and > 110 nm at 300 K.