  We investigated the spin-dependent transport properties of a lateral
spin-valve device with a 600 nm-long GaAs channel and ferromagnetic MnGa
electrodes with perpendicular magnetization. Its current-voltage
characteristics show nonlinear behavior below 50 K, indicating that tunnel
transport through the MnGa/GaAs Schottky barrier is dominant at low
temperatures. We observed clear magnetoresistance (MR) ratio up to 12% at 4 K
when applying a magnetic field perpendicular to the film plane. Furthermore, a
large spin-dependent output voltage of 33 mV is obtained. These values are the
highest in lateral ferromagnetic metal / semiconductor / ferromagnetic metal
spin-valve devices reported so far.
