Study of Electron Spin Diffusion and Relaxation Dynamics by Diffraction of transient spin grating in an Intrinsic GaAs/AlGaAs Quantum Well

Abstract

In this paper, the transient spin grating method was used to measure the attenuation rate of the diffraction signals of the intrinsic spin gratings of the intrinsic GaAs/AlGaAs quantum wells in different periods at room temperature, and the electron spin diffusion coefficient Ds = 121±6cm2/s was obtained. The electron spin diffusion coefficients of GaAs/AlGaAs quantum well were in good agreement with that of p-type GaAs/AlGaAs quantum well, indicating that the doping type for GaAs/AlGaAs quantum well has no significant effect on the diffusion rate of spin-polarized electrons. In this paper, the widely used formula of transient spin grating diffraction signal attenuation rate was used to fit the diffraction experimental results of the transient spin grating in the intrinsic GaAs/AlGaAs quantum well. The measured electron spin relaxation time was much shorter than that measured by the saturation absorption method. The reason for the deviation in the measured spin relaxation time was analyzed. The dynamic law of transient spin grating modulation attenuation over time was derived. The decay rate formula was modified, and the modified formula was used to fit the experimental data in the transient spin grating diffraction to obtain the spin relaxation time τs = 123 ps. The result was consistent with the measured electron spin relaxation time by the saturation absorption method.