New Types of Kitaev Candidates and the Role of Kitaev Interaction in Ordered Magnetism

The successful of Kitaev model in generating quantum spin liquid states and other intriguing physics has been motivating the seeking for Kitaev candidate materials. Previous works focus on heavy transition metal compounds, such as α-RuCl₃ with 4d electrons and Na₂IrO₃ with 5d electrons. Actually, for a long time, it was only these two types of candidates, which hinders the development of Kitaev physics. In this talk, I will report the discovery of new Kitaev candidates with 3d electrons, which include the CrI₃, CrGeTe₃, NiI₂, Na₃Co₂SbO₆, as well as a counterexample of Na₃Ni₂BiO₆. As we will see, the new candidates not only exhibit different spin values of S=1/2, 1 and 3/2, but also have their Kitaev terms arise from different mechanisms. Interestingly, by looking into the first-principle-based spin models of such systems, it is found that the Kitaev term can not only induce diverse anisotropies, but also alter the orders of the ground states. Our studies thus reveal an overlooked aspect of Kitaev interaction, that is it can also play an important role in ordered magnetism and interplay with, e.g., multiferroicity.