title: Exact ground states of a frustrated 2D magnet: deconfined fractional excitations at a first-order quantum phase transition.
abstract: 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.
authors.affiliation: Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Batista
authors.forename: S A
authors.initials: SA
authors.lastname: Trugman