Two-step melting of three-sublattice order in $S=1$ easy-axis triangular lattice antiferromagnets

Dariush Heidarian; Kedar Damle

doi:10.1140/epjb/e2018-90353-8

paper

Two-step melting of three-sublattice order in $S = 1$ easy-axis triangular lattice antiferromagnets

arXiv:1512.01346 · doi:10.1140/epjb/e2018-90353-8

Abstract

We consider $S = 1$ triangular lattice Heisenberg antiferromagnets with a strong single-ion anisotropy $D$ that dominates over the nearest-neighbour antiferromagnetic exchange $J$ . In this limit of small $J / D$ , we study low temperature ( $T \sim J ≪ D$ ) properties of such magnets by employing a low-energy description in terms of hard-core bosons with nearest neighbour repulsion $V \approx 4 J + J^{2} / D$ and nearest neighbour unfrustrated hopping $t \approx J^{2} /2 D$ . Using a cluster Stochastic Series Expansion (SSE) algorithm to perform sign-problem-free quantum Monte Carlo (QMC) simulations of this effective model, we establish that the ground-state three-sublattice order of the easy-axis spin-density $S^{z} (r)$ melts in zero field ( $B = 0$ ) in a {\em two-step} manner via an intermediate temperature phase characterized by power-law three-sublattice order with a temperature dependent exponent $η (T) \in [\frac{1}{9}, \frac{1}{4}]$ . For $η (T) < \frac{2}{9}$ in this phase, we find that the uniform easy-axis susceptibility of an $L \times L$ sample diverges as $χ_{L} \sim L^{2 - 9 η}$ at $B = 0$ , consistent with a recent prediction that the thermodynamic susceptibility to a uniform field $B$ along the easy axis diverges at small $B$ as $χ_{easy - axis} (B) \sim B^{- \frac{4 - 18 η}{4 - 9 η}}$ in this regime.

7 pages; two-column format; 8 figures

Two-step melting of three-sublattice order in S=1 easy-axis triangular lattice antiferromagnets

Abstract

References in corpus (9)

Two-step melting of three-sublattice order in $S = 1$ easy-axis triangular lattice antiferromagnets