Influence of Ising-anisotropy on the zero-temperature phase transition in the square lattice spin-1/2 J-J' model

Abstract

We use a variational mean-field like approach, the coupled cluster method (CCM) and exact diagonalization to investigate the ground-state order-disorder transition for the square lattice spin-half XXZ model with two different nearest-neighbor couplings $J$ and $J^{\prime }$. Increasing $J^{\prime }>J$ the model shows in the isotropic Heisenberg limit a second-order transition from semi-classical Néel order to a quantum paramagnetic phase with enhanced local dimer correlations on the $J^{\prime }$ bonds at about $J_c^{\prime }\sim \mathrm{2.5...3}J$. This transition is driven by the quantum competition between $J^{\prime }$ and $J$. Increasing the anisotropy parameter $\Delta >1$ we diminish the quantum fluctuations and thus the degree of competition. As a result the transition point $J_c^{\prime }$ is shifted to larger values. We find indications for a linear increase of $J_c^{\prime }$ with $\Delta$, i.e. the transition disappears in the Ising limit $\Delta \to \infty$.

8 pages, 4 figures

References in corpus (4)

• Some basic aspects of quantum phase transitions
• Influence of quantum fluctuations on zero-temperature phase transitions between collinear and noncollinear states in frustrated spin systems
• Quantum phase transitions in the J-J' Heisenberg and XY spin-1/2 antiferromagnets on square lattice: Finite-size scaling analysis
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• Frustrated Quantum Antiferromagnets: Application of High-Order Coupled Cluster Method
• A frustrated quantum spin-${\boldmath s}$ model on the Union Jack lattice with spins ${\boldmath s>1/2}$
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