Tunable energy bands and spin filtering in two-dimensional superlattices with spin-orbit interaction

We theoretically investigate the electronic energy bands and spin filtering tuned by Rashba spin-orbit coupling (SOC) and magnetic field in two-dimensional superlattices (2DSLs), where the square rods of quantum barriers, matrix, and wells are imposed periodically. It is shown that electronic energy spectra form a band structure and the energy levels are split up by the Rashba SOC. Correspondingly, the electrical conductance presents a "band-gap" structure against the electron energy. With manipulating the strength of SOC, the conductance in the "band" is enhanced for the spin-up electrons, while it is reduced for the spin-down electrons. Interestingly, by introducing a magnetic modulation, conductance curves for spin-up and spin-down electrons are translated in the different directions. As a result, high spin polarization is observed, and fully spin-polarized conductance is achieved in this 2DSL. Furthermore, the electronic wavefunctions have been obtained, which presents a clear picture of spin filtering. Our investigations achieve potential applications in spin quantum devices and spin filters. (C) 2012 American Institute of Physics. [doi:10.1063/1.3684715]