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Spin liquid ground state in a two dimensional non-frustrated spin model

G. Santoro·S. Sorella·L. Guidoni·A. Parola·E. Tosatti
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Abstract

We consider an exchange model describing two isotropic spin-1/2 Heisenberg antiferromagnets coupled by a quartic term on the square lattice. The model is relevant for systems with orbital degeneracy and strong electron-vibron coupling in the large Hubbard repulsion limit, and is known to show a spin-Peierls-like dimerization in one dimension. In two dimensions we calculate energy gaps, susceptibilities, and correlation functions with a Green's Function Monte Carlo. We find a finite spin gap and no evidence of any kind of order. We conclude that the ground state is, most likely, a spin liquid of resonating valence bonds.

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G. Santoro, S. Sorella, L. Guidoni, A. Parola, E. Tosatti. 1999-02-09. Spin liquid ground state in a two dimensional non-frustrated spin model. https://doi.org/10.1103/physrevlett.83.3065

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