Weak Ferromagnetic Exchange and Anomalous Specific Heat in ZnCu3(OH)6Cl2
arXiv:0801.2138 · doi:10.1103/PhysRevLett.101.027204
Abstract
Experimental evidence for a plethora of low energy spin excitations in the spin-1/2 kagome antiferromagnet ZnCu3(OH)6Cl2 may be understandable in terms of an extended Fermi surface of spinons coupled to a U(1) gauge field. We carry out variational calculations to examine the possibility that such a state may be energetically viable. A Gutzwiller-projected wavefunction reproduces the dimerization of a kagome strip found previously by DMRG. Application to the full kagome lattice shows that the inclusion of a small ferromagnetic next-nearest-neighbor interaction favors a ground state with a spinon Fermi surface.
4 pages, 3 figures, some clarifications to the text
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