Ground state properties of quantum triangular ice

S. A. Owerre

doi:10.1103/PhysRevB.93.094436

paper

Ground state properties of quantum triangular ice

arXiv:1511.01843 · doi:10.1103/PhysRevB.93.094436

Abstract

Motivated by recent quantum Monte Carlo (QMC) simulations of the quantum Kagome ice model by Juan Carrasquilla, et al., [Nature Communications 6, 7421 (2015)], we study the ground state properties of this model on the triangular lattice. In the presence of a magnetic field $h$ , the Hamiltonian possesses competing interactions between a $Z_{2}$ -invariant easy-axis ferromagnetic interaction $J_{\pm\pm}$ and a frustrated Ising term $J_{z}$ . As in the U(1)-invariant model, we obtain four classical distinctive phases, however, the classical phases in the $Z_{2}$ -invariant model are different. They are as follows: a fully polarized (FP) ferromagnet for large $h$ , an easy-axis canted ferromagnet (CFM) with broken $Z_{2}$ symmetry for small $h$ and dominant $J_{\pm\pm}$ , a {\it ferrosolid} phase with broken translational and $Z_{2}$ symmetries for small $h$ and dominant $J_{z}$ , and two lobes with $m = ⟨ S_{z} ⟩ = \pm 1/6$ for small $h$ and dominant $J_{z}$ . We show that quantum fluctuations are suppressed in this model, hence the large- $S$ expansion gives an accurate picture of the ground state properties. When quantum fluctuations are introduced, we show that the {\it ferrosolid} state is the ground state in the dominant Ising limit at zero magnetic field. It remains robust for $J_{z} \to \infty$ . With nonzero magnetic field the classical lobes acquire a finite magnetic susceptibility with no $S_{z}$ -order. We present the trends of the ground state energy and the magnetizations. We also present a detail analysis of the CFM.

13 pages with 19 figures

Ground state properties of quantum triangular ice

Abstract

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