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 $J_1-J_2$ Heisenberg model. The ground states of this model are exactly obtained at a first order quantum phase transition between two regions with different valence bond solid order parameters. 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 that signal the emergence of $Z_2$ gauge symmetry.

4 pages, 3 figures

References in corpus (4)

• "Deconfined" quantum critical points
• Geometry and the Hidden Order of Luttinger Liquids: the Universality of Squeezed Space
• Quasi-1D dynamics and nematic phases in the 2D Emery model
• Confinement and deconfinement of spinons in a frustrated spin-1/2 Heisenberg model

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