Ground-state phase diagram of the extended Kitaev-Heisenberg model on a honeycomb lattice

Recent studies on 4d and 5d transition-metal compounds on honeycomb lattices have unveiled possibility of realizing the Kitaev spin liquid. In this study, we consider the Kitaev-Heisenberg-Γ model on a honeycomb lattice, where symmetric-anisotropic interactions (Γ) exist in addition to the Kitaev and Heisenberg interactions. According to ab-initio calculations, this model describes the magnetism in spin-orbit-coupled honeycomb-lattice Mott insulators. We calculate the ground–state energy using series expansions, and obtain the phase diagram. This method has an advantage that can deal with infinite-size systems. We discuss our results by comparing them with the results so far obtained with various numerical methods [1-3]. [1] J. G. Rau, et al., Phys. Rev. Lett. 112, 077204 (2014). [2] A. Catuneanu, et al., npj Quantum Materials 3, 23 (2018). [3] M. Gohlke, et al., Phys. Rev. B 97, 075126 (2018).