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arXiv · 1409.0193

The spin-1/2 square-lattice J_1-J_2 model: The spin-gap issue

J. Richter·R. Zinke·D. J. J. Farnell
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Abstract

We use the coupled cluster method to high orders of approximation in order to calculate the ground-state energy, the ground-state magnetic order parameter, and the spin gap of the spin-1/2 J_1-J_2 model on the square lattice. We obtain values for the transition points to the magnetically disordered quantum paramagnetic phase of J_2^{c1}=0.454J_1 and J_2^{c2}= 0.588 J_1. The spin gap is zero in the entire parameter region accessible by our approach, i.e. for J_2 \le 0.49J_1 and J_2 > 0.58J_1. This finding is in favor of a gapless spin-liquid ground state in this parameter regime.

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J. Richter, R. Zinke, D. J. J. Farnell. 2014-08-31. The spin-1/2 square-lattice J_1-J_2 model: The spin-gap issue. https://doi.org/10.1140/epjb/e2014-50589-x

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