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

By J. Richter, J. Schulenburg. 2009

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AbstractWe 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 < $J_2^{c_1}$ and J2 > $J_2^{c_2}$ separated by a gapful quantum paramagnetic phase. We estimate $J_2^{c_1}$≈0.35J1 and $J_2^{c_2}$≈0.66J1.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/13989e555801c6dab434ffa2d9e2f73ed949ebbb