Orbital Ordering and Frustration of p-Band Mott Insulators

Journal Article · Fri May 23 00:00:00 EDT 2008 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.100.200406· OSTI ID:21132431

Congjun, Wu ^[1]

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1. Department of Physics, University of California, San Diego, California 92093 (United States)

We investigate the general structure of orbital exchange physics in Mott-insulating states of p-orbital systems in optical lattices. 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 deg. 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.

• OSTI ID: 21132431
• Journal Information: Physical Review Letters, Vol. 100, Issue 20; Other Information: DOI: 10.1103/PhysRevLett.100.200406; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DEGREES OF FREEDOM
EXCITATION
GROUND STATES
QUANTUM MECHANICS
ROTATION
SEMICLASSICAL APPROXIMATION
U-1 GROUPS