An application of the coupled-cluster method to the S= 1/2 triangular-lattice antiferromagnet

Abstract

The coupled-cluster method is applied to the spin- 1/2 triangular-lattice anisotropic antiferromagnet, a noncollinear and frustrated magnet with an anisotropy parameter first introduced by Singh and Huse (1989). Various physical quantities including the ground-state energy, the anisotropy susceptibility, the sublattice magnetization, and their critical exponents associated with the magnetic order-disorder quantum phase transition, are calculated by the systematic inclusion of two-spin correlations. These results are then compared and contrasted with those obtained from other methods such as series expansions and variational calculations. The feasibility of carrying out quantum Monte Carlo simulations using the results presented here is also discussed by drawing parallels with the coupled-cluster calculations on the square-lattice antiferromagnets.