Figure 2

Schematic mechanism.

(a) A schematic diagram of the PIAHE. A left circularly polarized light vertically irradiates on the samples, exciting spin polarized electrons. The drift of spin polarized electrons driven by the longitudinal electric field leads to a transverse PIAHE current. (b) A schematic diagrams of the ACPGE. A left circularly polarized light with a Gaussian distribution in space leads to a similar spin polarization distribution. Spin diffusion occurs and electron spin density gradient generates a diffused SPC in the sample plane (denoted by orange arrows). This radial SPC then induces a vortex current j via the mechanism of ACPGE (denoted by green arrows).