Special Quantum Matter Seminar

There has been a significant effort invested in exploring candidate material realizations of the Kitaev spin liquid on the honeycomb lattice. Aside from materials like Na2IrO3 and alpha-RuCl3, recent work has suggested that certain cobaltates might also realize this physics. Early experiments on a set of cobaltates from Cava, Ong, and Armitage, provided tantalizing hints of a field-induced spin liquid in this new class of materials. I will review some of these results, and then discuss some of our numerical work (density-functional theory, exact diagonalization, DMRG and variational wavefunctions) which suggests that these systems might in fact be realizing a distinct type of spin liquid (SL) driven by third-neighbor frustration of an XY ferromagnet. We argue that such models might host a nearby Dirac liquid state which could potentially be unstable to forming various weakly gapped spin liquids (which may preserve or break certain symmetries). Our results provide a reasonable explanation of the measured teraHertz spin dynamics and thermal conductivity in these systems.