title: Electromagnetic pulse-driven spin-dependent currents in semiconductor quantum rings.
abstract: We investigate the non-equilibrium charge and spin-dependent currents in a quantum ring with a Rashba spin-orbit interaction (SOI) driven by two asymmetric picosecond electromagnetic pulses. The equilibrium persistent charge and persistent spin-dependent currents are investigated as well. It is shown that the dynamical charge and the dynamical spin-dependent currents vary smoothly with a static external magnetic flux and the SOI provides a SU(2) effective flux that changes the phases of the dynamic charge and the dynamic spin-dependent currents. The period of the oscillation of the total charge current with the delay time between the pulses is larger in a quantum ring with a larger radius. The parameters of the pulse fields control to a certain extent the total charge and the total spin-dependent currents. The calculations are applicable to nanometre rings fabricated in heterojunctions of III-V and II-VI semiconductors containing several hundreds of electrons.
authors.affiliation: Institut für Physik, Martin-Luther Universität Halle-Wittenberg, Heinrich-Damerow-Straße 4 06120 Halle, Germany.
authors.forename: Zhen-Gang
authors.initials: ZG
authors.lastname: Zhu
authors.forename: Jamal
authors.initials: J
authors.lastname: Berakdar