TWO-DIMENSIONAL QUANTUM ANTIFERROMAGNETS

Grégoire Misguich, C. Lhuillier

Subir Sachdev A

Philippe Sindzingre, C. Lhuillier, J.-B. Fouet

We describe four phases found in two-dimensional quantum antiferromagnets. Two of them display long range order at T = 0: the Néel state and the Valence Bond Crystal. The last two are Spin-Liquids. Properties of these different states are shortly described and likely conditions of their occurrence outlined.

Eduardo Fradkin

Philippe Sindzingre, C. Lhuillier, J.-B. Fouet

We describe four phases found in two-dimensional quantum antiferromagnets. Two of them display long range order at T=0: the Néel state and the Valence Bond Crystal. The last two are Spin-Liquids. Properties of these different states are shortly described and likely conditions of their occurence outlined.

C. Y. Pan

A real space renormalization group method is applied to study the spin-1/2 two-dimensional anisotropic Heisenberg antiferromagnets. We carry out the calculation on a 5×5 cluster by using a variational approach. The ground-state energy per site is estimated as e0=−0.6845±0.0005 which is in good agreement with other numerical estimates. We also calculate the different ground state energies when anisotropy changes. By comparing with 3×3 cluster calculation the resulting threshold for long range order drops and the curve of the renormalization group parameter vs. anisotropy shows no hint of discontinuity over a wide range of anisotropic parameters. Hence, our calculation suggests that long-range order exists for the ground-state of the spin-1/2 Heisenberg antiferromagnets in two dimensions.