  We investigate the electron transport through a two-dimensional semiconductor
with a nonuniform Rashba spin-orbit interaction. Due to the combination of the
coherence effect and the Rashba interaction, a spontaneous spin-polarized
current emerges in the absence of any magnetic material and magnetic field. For
a two-terminal device, only the local current contains polarization; however,
with a four-terminal setup, a polarized total current is produced. This
phenomenon may offer a novel way for generating a spin-polarized current,
replacing the traditional spin-injection method.
