Large spin-valve effect in a lateral spin-valve device based on ferromagnetic semiconductor GaMnAs

We investigate the spin-dependent transport properties of a lateral spin-valve device based on the ferromagnetic semiconductor GaMnAs. This device is composed of a GaMnAs channel layer grown on GaAs with a narrow trench across the channel. Its current–voltage characteristics show tunneling behavior. Large magnetoresistance (MR) ratios of more than ~10% are obtained. These values are much larger than those (~0.1%) reported for lateral-type spin metal–oxide–semiconductor field-effect transistors. The magnetic field direction dependence of the MR curve differs from that of the anisotropic magnetoresistance of GaMnAs, which confirms that the MR signal originates from the spin-valve effect between the GaMnAs electrodes.