2012/04/11 by P. H. Y. Li, R. F. Bishop, D. J. J. Farnell +1 · 1 citation
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.86.144404
published as Phys. Rev. B 86 (2012) 144404
arxiv created 2012/04/11 · arxiv updated 2015/06/04
We use the coupled cluster method in high orders of approximation to make a comprehensive study of the ground-state (GS) phase diagram of the spin-1/2 J1--J2--J3 model on a two-dimensional honeycomb lattice with antiferromagnetic (AFM) interactions up to third-nearest neighbors. Results are presented for the GS energy and the average local on-site magnetization. With the nearest-neighbor coupling strength J1 ≡ 1 we find four magnetically ordered phases in the parameter window J2,J3 ∈ [0,1], namely the Néel (N), striped (S), and anti-Néel (aN) collinear AFM phases, plus a spiral phase. The aN phase appears as a stable GS phase in the classical version of the model only for values J3<0. Each of these four ordered phases shares a boundary with a disordered quantum paramagnetic (QP) phase, and at several widely separated points on the phase boundaries the QP phase has an infinite susceptibility to plaquette valence-bond crystalline order. We identify all of the phase boundaries with good precision in the parameter window studied, and we find three tricritical quantum critical points therein at: (a) (J2c1,J3c1)=(0.51 ± 0.01,0.69 ± 0.01) between the N, S, and QP phases; (b) (J2c2,J3c2)=(0.65 ± 0.02,0.55 ± 0.01) between the S, spiral, and QP phases; and (c) (J2c3,J3c3)=(0.69 ± 0.01,0.12 ± 0.01) between the spiral, aN, and QP phases.