Two-dimensional S=1/2 antiferromagnet on a plaquette lattice

Abstract

We consider a simplified model of the magnetic structure of the two-dimensional compound $Ca{V}_4{O}_9$ in terms of interacting square plaquettes of spins with two distinct antiferromagnetic exchange constants. We analyze the competition between two types of singlet ground states and the Neel ordered one in terms of respectively, numerical cluster expansion and nonlinear spin wave theory. The resulting phase diagram agrees well with known Quantum Monte Carlo results and suggests a first order transition between ordered and singlet ground states as a function of the exchange constants.

revtex, 5 pages, 2 Postscript figures

References in corpus (3)

• Phase diagram of depleted Heisenberg model for CaV4O9
• Plaquette Resonating-Valence-Bond Ground State of CaV${}_4$O${}_9$
• Spin Gap in Two-Dimensional Heisenberg Model for CaV${}_4$O${}_9$

Cited by in corpus (3)

• The antiferromagnetic spin 1/2 chain with competing dimers and plaquettes: Numerical versus exact results
• High-Order Coupled Cluster Method (CCM) Calculations for Quantum Magnets with Valence-Bond Ground States
• Projective symmetry group classification of Abrikosov fermion mean-field ansätze on the square-octagon lattice