Spontaneous spin-polarized current in a nonuniform Rashba interaction system

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.