Probing Interaction-Induced Ferromagnetism in Optical Superlattices

ORAL

Abstract

We analyze how to use ultracold fermionic atoms loaded in optical superlattices for a controllable preparation and detection of interaction-induced ferromagnetism. First, we discuss how to experimentally achieve Nagaoka ferromagnetism in an array of isolated plaquettes (four lattice sites arranged in a square). Next, we allow for weak interplaquette tunneling and analyze the occurrence of itinerant ferromagnetism. Since ferromagnetism is unstable in the presence of weak interplaquette couplings, we propose to mediate long-range ferromagnetic correlations via double-exchange processes by exciting atoms to an excited vibrational band. We calculate the phase diagram of the two-band plaquette array and discuss conditions for the stability and robustness of the ferromagnetic phases in this system. Experimental implementations of the proposed schemes are discussed.

*This work was supported in part by NSF, NIST, ITAMP, CUA and DARPA.

Authors

  • Javier von Stecher

    • JILA and Department of Physics, University of Colorado, Boulder, Colorado

  • Eugene Demler

    • Physics Department, Harvard University, Cambridge-MA, 20138
    • Physics Department, Harvard University, Cambridge-MA, 20138.
    • Harvard University

  • Mikhail Lukin

    • Harvard, ITAMP
    • Harvard Physics Dpt, CUA
    • Physics Dept., Harvard U.
    • Harvard University
    • Physics Department, Harvard University, Cambridge-MA, 20138
    • Physics Department, Harvard University, Cambridge-MA, 20138.

  • Ana Maria Rey

    • University of Colorado, JILA, NIST
    • JILA, University of Colorado at Boulder
    • JILA, NIST, and the University of Colorado
    • JILA and Department of Physics, University of Colorado, Boulder, Colorado
    • JILA, NIST and Department of Physics, University of Colorado