Spin-$S$ designer hamiltonians and the square lattice $S=1$ Haldane nematic

Abstract

We introduce a strategy to write down lattice models of spin rotational symmetric Hamiltonians with arbitrary spin-$S$ that are Marshall positive and can be simulated efficiently using world line Monte Carlo methods. As an application of our approach we consider a square lattice $S=1$ model for which we design a $3\times 3$ - spin plaquette interaction. By numerical simulations we establish that our model realizes a novel "Haldane nematic" phase that breaks lattice rotational symmetry by the spontaneous formation of Haldane chains, while preserving spin rotations, time reversal and lattice translations. By supplementing our model with a two-spin Heisenberg interaction, we present a study of the transition between Néel and Haldane nematic phase, which we find to be of first order.