Scanning Kerr Microscopy of the Spin Hall Effect in n-Doped GaAs with Various Doping Concentration

We investigated the doping concentration (N (D)) dependence of the extrinsic spin Hall effect (SHE) in n-doped GaAs with N (D) raging from 3x10(16) cm(-3) to 5x10(17) cm(-3). By using scanning Kerr microscopy (SKM) measurements, we observed the Kerr rotation signal due to the spin accumulation near the channel edges in all the samples with different N (D). Moreover, the position and in-plane magnetic field dependence of the Kerr rotation signal are found to vary with N (D). We analyzed the N (D) dependence of the spin Hall conductivity by taking account of the N (D)-dependent spin lifetime based on the typical drift-diffusion model.