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Past Events
Classification of Quantum Phases for the Star-lattice Antiferromagnet Via a Projective Symmetry Group Analysis
| Speaker: | Dr. Tingpong CHOY |
| Affiliation: | Toroton University |
| Date: | December 18, 2009 (Fri) |
| Time: | 11:00 a.m. - 12:00 n.n. |
| Venue: | Room 522, 5/F, Chong Yuet Ming Physics Building, HKU |
Abstract:
We study possible quantum ground states of the Heisenberg antiferromagnet on the star lattice, which may be realized in the recently discovered polymeric Iron Acetate, Fe3(μ3-O)(μ-OAc)6(H2O)3[Fe3(μ3-O)(μ-OAc)7.5]2... 7H2O. Even though the FeIII moment in this material carries spin-5/2 and the system eventually orders magnetically at low temperatures, the magnetic ordering temperature is much lower than the estimated Curie-Weiss temperature, revealing the frustrated nature of the spin interactions. Anticipating that a lower spin analog of this material may be synthesized in future, we investigate the effect of quantum fluctuations on the star-lattice antiferromagnet using a large-N Sp(N) mean field theory and a projective symmetry group analysis for possible bosonic quantum spin liquid phases. It is found that there exist only two distinct gapped Z2 spin liquid phases with bosonic spinons for non-vanishing nearest-neighbor valence-bond-amplitudes. In particular, the spin liquid phase which has a lower energy in the nearest-neighbor exchange model can be stabilized for relatively higher spin magnitudes.
Coffee and tea will be served 20 minutes prior to the seminar.