4d, 5d transition-metal compounds on a honeycomb lattice, such as \alpha-RuCl3 and Na2IrO3, are known to possess Kitaev interactions that are of bond-dependent ferromagnetic Ising type. This exotic property is caused by a cooperation of the spin-orbit interaction, electron correlation, and the geometric structure. This feature makes us expect to emerge unconventional superconducting states, when carriers are doped to these compounds. Indeed, theoretical calculations based on slave-particle mean-field theory for a hole-doped extended Kitaev model showed phase diagrams for superconducting states that have (chiral) d-wave, (chiral) p-wave, and topological p-wave Cooper pair symmetries depending on the hole concentration and the strengths of interactions [1-4]. However, the results strongly depend on the application of a gauge field associated with the slave particle method and there is still a debate as to which superconducting states appear. Thus, research using reliable numerical methods is required. In this study, we theoretically investigate a hole-doped extended Kitaev model using a real-space renormalized mean-field theory within a Gutzwiller approximation. We examine the superconducting states that appear when the hole concentration and the strengths of the interactions are changed and compare them with the results of the previous studied. We will also discuss the competing ordered states including the possibility of the phase separation.
[1] T. Hyart, et al., Phys. Rev. B 85, 140510(R) (2012).
[2] Y.-Z. You, et al., Phys. Rev. B 86, 085145 (2012).
[3] S. Okamoto, Phys. Rev. B 87, 064508 (2013).
[4] J. Schmidt, et al., Phys. Rev. B 97, 014504 (2018).
SS was supported by JSPS KAKENHI (Grant No. 19K03721) from MEXT, Japan.