Large spatial distribution of spin accumulation in wide Au channel

•We investigated Au channel width effect on spin accumulation using non-local measurement.•Spin accumulation decays with increasing Au channel width at a fixed channel length.•Large spatial distribution of spin current is initiated from inhomogeneous spin injection.•It can be well understood by introducing the effective channel length.

Non local spin valve measurements for lateral Permalloy(Py)/Au/Py spin valve devices with various Au channel widths were carried out in two viable voltage probe configurations. With increasing the channel width at a fixed channel length, the magnitude of spin valve signal (ΔR) decays for both configurations. Non-zero ΔR is observed up to 3 μm in width while no spin signal is observed even narrower width of 0.7 μm when the current and voltage probes are located on the same side or opposite side with respect to the current path respectively. The magnitude of ΔR is strongly affected by the location of voltage probe on both ends of the detector as well as channel width. Large spatial distribution of spin current is initiated from inhomogeneous spin injection close to the current path and can be well understood by introducing the effective channel length.