Measuring spin diffusion of electrons in bulk n-GaAs using circularly dichromatic absorption difference spectroscopy of spin gratings

Circular dichromatic absorption difference spectroscopy is developed to measure the spin diffusion dynamics of electrons in bulk n-GaAs. This spectroscopy has higher detection sensitivity over homodyne detection of spin-grating-diffracted signal. A model to describe circular dichromatic absorption difference signal is derived and used to fit experimental signal to retrieve decaying rate of spin gratings. A spin diffusion constant of D-s=201 +/- 25 cm(2)/s for bulk n-GaAs has been measured at room temperature using this technique and is close to electron diffusion constant (D-c), which is much different from the case in GaAs quantum wells where D-s is markedly less than D-c.

NSF 60678009 60490295108742476062540510734060MOE of China 20050558030 The authors would like to thank Dr. Zhimin Liao for his help in improving the English writing of this letter. This work is supported partially by the NSF of China under Grant Nos. 60678009, 60490295, 10874247, 60625405, and 10734060, and also by the doctoral specialized fund of the MOE of China under Grant No. 20050558030.