Exotic superconductivity in the doped Kitaev quantum spin liquid

The Kitaev model on a honeycomb lattice proposed by Kitaev in 2006 [1] has attracted great attention as a rare theoretical model whose ground state can be exactly obtained and realizes a quantum spin liquid. Recently, the possibility of realizing unconventional superconductivity by doping carriers into the Kitaev quantum spin liquid has been discussed. To theoretically explore this, an itinerant extension of the Kitaev model with the prohibition of double occupancy—the tJ-Kitaev model—has been introduced, and mean-field studies have suggested possible p-wave and d+id-wave superconductivity [2–4], although studies beyond the mean-field approximation remain limited. In this work, we investigate the emergence of superconductivity in the tJ-Kitaev model using the many-variable variational Monte Carlo (mVMC) method [5]. By systematically varying the doping concentration and interaction strength, we have found that triplet superconductivity emerges and coexists with ferromagnetism for ferromagnetic Kitaev interactions. 

References:

[1] A. Kitaev, Ann. Phys. (N. Y.) 321, 2 (2006). 

[2] T. Hyat et al., Phys. Rev. B 85, 140510(R) (2012).

[3] Y.-Z. You et al., Phys. Rev. B 86, 085145 (2012).

[4] S. Okamoto, Phys. Rev. B 87, 064508 (2013).

[5] T. Misawa et al., Comp. Phys. Commun. 235, 447 (2019).