Dominant Kitaev interactions in the honeycomb materials Na3Co2SbO6 and Na2Co2TeO6

Abstract

Cobaltates with 3d based layered honeycomb structure were recently proposed as Kitaev magnets and putative candidates to host the long-sought Kitaev spin liquid. Here we present inelastic neutron scattering results down to 50 mK for powder samples of Na3Co2SbO6 and Na2Co2TeO6, with high resolution in regions of low momentum and energy transfers. We compare the experimental data below the antiferromagnetic zigzag ordering temperature with dynamical structure factors obtained within spin wave theory. We search the wide parameter range of a K-J1-Γ-Γ′-J3 spin 1/2 model and identify the best fits to constant momentum cuts of the inelastic neutron data. The powder average limits our ability to uni..