Non-Local and Local Spin Signals in a Lateral Spin Transport Device With ${\rm Co}_{2}{\rm FeAl}_{0.5}{\rm Si}_{0.5}/n$ -GaAs Schottky Tunnel Junctions

We investigated magnetoresistance (MR) effects in four-terminal (4T) nonlocal and local measurements of a lateral spin transport device with Co₂FeAl_0.5Si_0.5 (CFAS)/ -GaAs Schottky tunnel junctions. Clear voltage changes as a function of magnetic field were observed in both measurements, and these signals were confirmed to originate from spin injection, transport, and detection in the device. The values of voltage change in both measurements, ΔV_local and ΔV_local, increased linearly as a function of bias current. The MR ratio in local measurement could be explained by the conductivity mismatch theory. The nonlocal and local measurements in various circuit configurations indicated that the magnitude of was ΔV_local enhanced not only by an increase in spin transport length in the n-GaAs channel but also by an enhancement of spin detection efficiency at the CFAS/n-GaAs interface.