paper

Ordered states in the Kitaev-Heisenberg model: From 1D chains to 2D honeycomb

arXiv:1712.07418 · doi:10.1038/s41598-018-19960-4

Abstract

We study the ground state of the 1D Kitaev-Heisenberg (KH) model using the density-matrix renormalization group and Lanczos exact diagonalization methods. We obtain a rich ground-state phase diagram as a function of the ratio between Heisenberg ( and Kitaev () interactions. Depending on the ratio, the system exhibits four long-range ordered states: ferromagnetic- , ferromagnetic-, staggered-, Néel-, and two liquid states: Tomonaga-Luttinger liquid and spiral-. The two Kitaev points and are singular. The -dependent phase diagram is similar to that for the 2D honeycomb-lattice KH model. Remarkably, all the ordered states of the honeycomb-lattice KH model can be interpreted in terms of the coupled KH chains. We also discuss the magnetic structure of the K-intercalated RuCl, a potential Kitaev material, in the framework of the 1D KH model. Furthermore, we demonstrate that the low-lying excitations of the 1D KH Hamiltonian can be explained within the combination of the known six-vertex model and spin-wave theory.

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