Search for Kitaev interactions and vortex spin dynamics in a spin-orbit coupled triangular magnet

We propose to explore the spin dynamics of a hexagonal magnet with Co2+ ions with spin-orbit entangled J_eff=1/2 magnetic moments where bond-dependent anisotropic (Kitaev) interactions are expected, but so far evidence for such interactions has only been found in honeycomb structures for Ru3+ and Ir4+ ions. We have recently characterized the magnetic phase diagram of hexagonal Na2BaCoP2O8 via neutron diffraction and observed a surprising phase in applied field with q-vector moving along the zone boundary upon varying field, which may be related to the so-called vortex crystal phase expected to be stabilized when sub-leading ferromagnetic Kitaev interactions accompany antiferromagnetic Heisenberg exchange. Here we propose to study the spin dynamics as a function of applied field and search for specific signatures of Kitaev interactions and vortex physics in single crystals.