Investgating the evolution of Kitaev interactions in a family of triangular-lattice Kitaev materials

Kitaev model offers a novel approach to quantum spin liquids, which holds highly entangled ground states and fractional excitations. However, the way to realize dominated Kitaev interactions in real materials is still in the exploratory phase.
In this proposal, we aim to investigate the evolution of Kitaev interactions in a family of triangular-lattice Kitaev materials, CoX2(X = Cl, Br). Co-based materials are proposed to hold Kitaev interactions through spin-orbital coupled effective 1/2 spin states. Previous INS study in CoI2 has shown the existence of bond-dependent anisotropic interaction. Meanwhile, the theorists have found that the anions in Co-based materials may modified the Kitaev interactions. This conclusion has been partly verified in RuX3 (X = Cl, Br, I) but trapped in the synthesize of large, high quality single crystals.
We plan to carry inelastic neutron scattering study in the large and high-quality single crystals of CoCl2 and CoBr2 to find the evidence of Kitaev interactions. We will probe the spin-dynamics and try to give a low-energy effective spin models. We will focus on the evolution of Kiteav interactions in these systems and comparing with previous result in CoI2.
This study may reveal how to modify the Kiteav interactions and help for realizing more ideal platform of Kitaev physics.