Frustrated Orbital Exchange Models in p-band Mott Insulators

ORAL

Abstract

We investigate the general structure of orbital exchange physics in Mott-insulating states of p-orbital systems. Orbital orders occur in both the triangular and kagome lattices. In contrast, orbital exchange in the honeycomb lattice is frustrated as described by a novel quantum 120$^{\circ}$ model. Its classical ground states are mapped into configurations of the fully packed loop model with an extra U(1) rotation degree of freedom. Quantum orbital fluctuations select a six-site plaquette ground state ordering pattern in the semiclassical limit from the ``order from disorder'' mechanism. This effect arises from the appearance of a zero energy flat band of orbital excitations.

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Authors

  • Congjun Wu

    • Department of Physics, University of California, San Diego
    • Department of Physics, University of California, San Diego, California 92093
    • University of California, San Diego
    • Department of Physics, University of California, San Diego, CA 92093