2002/08/19 by Luca Capriotti, Capriotti, Luca, Federico Becca +5
Physics and Astronomy · #FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.cond-mat/0208371
10 pages, 7 figures, to be published in the Proceedings of the "Enrico Fermi" Summer School (course CLI)
arxiv created 2002/08/19 · arxiv updated 2009/11/30
Twenty-five years after the first proposal, the question whether the ground state of a frustrated spin-half system is well described by a spin-liquid Resonating Valence Bond (RVB) wave function is still controversial. A physically transparent representation of a RVB state can be obtained in fermionic representation with a standard BCS-type pairing wave function, working in the subspace with fixed number of electrons and no double occupancies. In this work, we show that, using this variational wave function with a careful parameterization of the pairing function, it is possible to obtain an extremely accurate \em ansatz for the ground state of the Heisenberg antiferromagnet with next-nearest neighbors interactions (J1-J2 model) in the regime of strong frustration. Indeed, in the spin-half realization of this model, it is known that the combined effect of frustration and zero-point motion interferes with the mechanism of spontaneously broken symmetry, giving rise to a non-magnetic phase of purely quantum-mechanical nature (J2/J1≃ 0.5). This wave function is proposed to represent the generic spin-half RVB ground state in spin liquids.