EPL, 83 (2008) 47004
DOI: 10.1209/0295-5075/83/47004

The quantum J₁-J'₁-J₂ spin-1 Heisenberg model: Influence of the interchain coupling on the ground-state magnetic ordering in 2D

R. F. Bishop^{1, 2}, P. H. Y. Li^{1, 2}, R. Darradi³ and J. Richter<sup>3

1</sup>  School of Physics & Astronomy, Schuster Building, The University of Manchester - Manchester, M13 9PL, UK, EU
²  School of Physics & Astronomy, University of Minnesota - 116 Church St. SE, Minneapolis, MN 55455, USA
³  Institut für Theoretische Physik, Universität Magdeburg - 39016 Magdeburg, Germany, EU

received 21 April 2008; accepted in final form 25 June 2008; published August 2008
published online 30 July 2008

Abstract
We study the phase diagram of the isotropic J₁- J'₁-J₂ Heisenberg model for spin-1 particles on an anisotropic square lattice, using the coupled-cluster method. We find no evidence for an intermediate phase between the Néel and stripe states, as compared with all previous results for the corresponding spin-1/2 case. However, we find a quantum tricritical point at J'₁/J₁ 0.66 0.03, J₂/J₁ 0.35 0.02, where a line of second-order phase transitions between the quasi-classical Néel and stripe-ordered phases (for J'₁/J₁ 0.66) meets a line of first-order phase transitions between the same two states (for J'₁/J₁ 0.66).

PACS
75.10.Jm - Quantized spin models.
75.30.Gw - Magnetic anisotropy.
75.50.Ee - Antiferromagnetics.

© EPLA 2008