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.

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