title: Spin currents in a coherent exciton gas.
abstract: We report the observation of spin currents in a coherent gas of indirect excitons. The realized long-range spin currents originate from the formation of a coherent gas of bosonic pairs--a new mechanism to suppress the spin relaxation. The spin currents result in the appearance of a variety of polarization patterns, including helical patterns, four-leaf patterns, spiral patterns, bell patterns, and periodic patterns. We demonstrate control of the spin currents by a magnetic field. We also present a theory of coherent exciton spin transport that describes the observed exciton polarization patterns and indicates the trajectories of the spin currents.
authors.affiliation: Department of Physics, University of California at San Diego, La Jolla, California 92093-0319, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: High
authors.affiliation: Department of Physics, University of California at San Diego, La Jolla, California 92093-0319, USA.
authors.forename: A T
authors.initials: AT
authors.lastname: Hammack
authors.affiliation: Department of Physics, University of California at San Diego, La Jolla, California 92093-0319, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Leonard
authors.affiliation: Department of Physics, University of California at San Diego, La Jolla, California 92093-0319, USA.
authors.forename: Sen
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Physics, University of California at San Diego, La Jolla, California 92093-0319, USA.
authors.forename: L V
authors.initials: LV
authors.lastname: Butov
authors.affiliation: Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague, Czech Republic.
authors.forename: T
authors.initials: T
authors.lastname: Ostatnický
authors.affiliation: Laboratoire Charles Coulomb, Université Montpellier 2, CNRS, UMR 5221, F-34095 Montpellier, France.
authors.forename: M
authors.initials: M
authors.lastname: Vladimirova
authors.affiliation: Laboratoire Charles Coulomb, Université Montpellier 2, CNRS, UMR 5221, F-34095 Montpellier, France and School of Physics and Astronomy, University of Southampton, SO17 1BJ Southampton, United Kingdom and Spin Optics Laboratory, State University of Saint Petersburg, 1 Ulianovskaya 198504, Russia.
authors.forename: A V
authors.initials: AV
authors.lastname: Kavokin
authors.affiliation: Mediterranean Institute of Fundamental Physics, 31 via Appia Nuova, Rome 00040, Italy.
authors.forename: T C H
authors.initials: TC
authors.lastname: Liew
authors.affiliation: Materials Department, University of California at Santa Barbara, Santa Barbara, California 93106-5050, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Campman
authors.affiliation: Materials Department, University of California at Santa Barbara, Santa Barbara, California 93106-5050, USA.
authors.forename: A C
authors.initials: AC
authors.lastname: Gossard