Enhancement of the spin signal in permalloy/gold multiterminal nanodevices by lateral confinement

We present experiments on a series of permalloy/gold lateral spin valves which show that their magnetoresistance (MR) is enhanced by about 100% in device geometries confining laterally the spin accumulation. We present the interpretation of this enhancement in the frame of the theory of diffusive spin transport in lateral nanostructures and we show that the MR enhancement can be generally related to the enhancement of both spin accumulation and current spin polarization.