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arXiv · 0909.3723

The spin-1/2 J1-J2 Heisenberg antiferromagnet on the square lattice: Exact diagonalization for N=40 spins

J. Richter·J. Schulenburg
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Abstract

We present numerical exact results for the ground state and the low-lying excitations for the spin-1/2 J1-J2 Heisenberg antiferromagnet on finite square lattices of up to N=40 sites. Using finite-size extrapolation we determine the ground-state energy, the magnetic order parameters, the spin gap, the uniform susceptibility, as well as the spin-wave velocity and the spin stiffness as functions of the frustration parameter J2/J1. In agreement with the generally excepted scenario we find semiclassical magnetically ordered phases for J2 < J2^{c1} and J2 > J2^{c2} separated by a gapful quantum paramagnetic phase. We estimate J2^{c1} \approx 0.35J1 and J2^{c2} \approx 0.66J1.

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J. Richter, J. Schulenburg. 2009-09-21. The spin-1/2 J1-J2 Heisenberg antiferromagnet on the square lattice: Exact diagonalization for N=40 spins. https://doi.org/10.1140/epjb/e2009-00400-4

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