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Nonlinear Sigma model method for the J1-J2 Heisenberg model: disordered ground state with plaquette symmetry

Ken'ichi Takano·Yoshiya Kito·Yoshiaki Ono·Kazuhiro Sano
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Abstract

A novel nonlinear sigma model method is proposed for the two-dimensional J1-J2 model, which is extended to include plaquette-type distortion. The nonlinear sigma model is properly derived without spoiling the original spin degrees of freedom. The method shows that a single disordered phase continuously extends from a frustrated uniform regime to an unfrustrated distorted regime. By the continuity and Oshikawa's commensurability condition, the disordered ground states for the uniform J1-J2 model are plaquette states with four-fold degeneracy.

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Ken'ichi Takano, Yoshiya Kito, Yoshiaki Ono, Kazuhiro Sano. 2003-10-29. Nonlinear Sigma model method for the J1-J2 Heisenberg model: disordered ground state with plaquette symmetry. https://doi.org/10.1103/physrevlett.91.197202

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