Nonlinear electron and spin transport in semiconductor superlattices
L. Barletti (Universita' di Firenze, Italy), L. L. Bonilla (Universidad Carlos III de Madrid, Spain), M. Alvaro (Universidad Carlos III de Madrid, Spain)
Nonlinear charge transport in strongly coupled semiconductor superlattices is described by two-miniband Wigner-Poisson kinetic equations with BGK collision terms. The hyperbolic limit, in which the collision frequencies are of the same order as the Bloch frequencies due to the electric field, is investigated by means of the Chapman-Enskog perturbation technique, leading to nonlinear drift-diffusion equations for the two miniband populations. In the case of a lateral superlattice with spin-orbit interaction, the corresponding drift-diffusion equations are used to calculate spin-polarized currents and electron spin polarization. Numerical solutions show stable self-sustained oscillations of the current and the spin polarization through a voltage biased lateral superlattice thereby providing an example of superlattice spin oscillator.