Global phase diagram, possible chiral spin liquid, and topological superconductivity in the triangular Kitaev–Heisenberg model

Abstract

The possible ground states of the undoped and doped Kitaev-Heisenberg model\non a triangular lattice are studied. For the undoped system, a combination of\nthe numerical exact diagonalization calculation and the four-sublattice\ntransformation analysis suggests one possible exotic phase and four\nmagnetically ordered phases including a collinear stripe pattern and a\nnoncollinear spiral pattern in the global phase diagram. The exotic phase near\nthe antiferromagnetic (AF) Kitaev point is further investigated by using the\nSchwinger-fermion mean-field method, and we obtain an energetically favorable\n$Z_2$ chiral spin liquid with a Chern number $\\pm2$ as a promising candidate.\nAt finite doping, we find that the AF Heisenberg coupling supports an $s$-wave\nor a $d_{x^2-y^2}+id_{xy}$-wave superconductivity (SC), while the AF and the\nferromagnetic Kitaev interactions favor a $d_{x^2-y^2}+id_{xy}$-wave SC and a\ntime-reversal invariant topological $p$-wave SC, respectively. Possible\nexperimental realizations and related candidate materials are also discussed.\n