Abstract:
In this talk we are going to present our theoretical investigations on spin dynamics of semiconductors under various conditions. It is shown from a fully microscopic kinetic-spin-Bloch-equation (KSBE) approach [1] that the single-particle approach is inadequate in accounting for the spin relaxation/dephasing (R/D) both in the time domain and the spacial domain. The momentum dependence of the effective magnetic field (the Dresselhaus and the Rashba terms) and the momentum dependence of the spin diffusion rate along the special gradient all serve as inhomogeneous broadenings. It is pointed out that in the presence of inhomogeneous broadening, any scattering, including the carrier-carrier Coulomb scattering, can cause irreversible spin R/D. Moreover, besides the spin R/D channel the scattering provides, it also gives rise to the counter effect to the inhomogeneous broadening. The scattering tends to drive carriers to a more homogeneous states and therefore suppresses the inhomogeneous broadening. Finally, this approach is valid in both strong and weak scattering regime and can be used to study systems far away from the equilibrium such as electrons of high spin polarization and/or electrons with strong electric field (hot electrons). Some common believes in the literature have been shown to be incorrect and many novel effects are predicted from our theory. Many of our predictions have been realized experimentally.
[1] M. W. Wu, J. H. Jiang, and M. Q. Weng, Phys. Rep. 493, 61 (2010)
Coffee and tea will be served 20 minutes prior to the seminar.