Exact ground states of a frustrated 2D magnet: deconfined fractional excitations at a first-order quantum phase transition.
We introduce a frustrated spin 1/2 Hamiltonian which is an extension of the two dimensional J1-J2 Heisenberg model. The ground states of this model are exactly obtained at a first-order quantum phase transition between two valence bond crystals. At this point, the low energy excitations are deconfined spinons and spin-charge separation occurs under doping in the limit of low concentration of holes. In addition, this point is characterized by the proliferation of topological defects.
Batista
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Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Trugman
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SA