Strategy to extract Kitaev interaction using symmetry in honeycomb Mott insulators

The Kitaev spin liquid, a ground state of the bond-dependent Kitaev model in a honeycomb lattice has been a center of attraction, since a microscopic theory to realize such an interaction in solid-state materials was discovered. A challenge in real materials though is the presence of the Heisenberg and another bond-dependent Gamma interactions detrimental to the Kitaev spin liquid, and there have been many debates on their relative strengths. Here we offer a strategy to extract the Kitaev interaction out of a full microscopic model by utilizing the symmetries of the Hamiltonian. Two tilted magnetic field directions related by a two-fold rotational symmetry generate distinct spin excitations originated from a specific combination of the Kitaev and Gamma interactions. Together with the in- and out-of-plane magnetic anisotropy, one can determine the Kitaev and Gamma interactions separately. Dynamic spin structure factors are presented to motivate future experiments. The proposed setups will advance the search for Kitaev materials. The Kitaev model describes bond dependent interactions on a 2D honeycomb lattice and is often associated with experiments to realise a quantum spin liquid state; however, despite many potential candidates, data on such materials are complex to interpret. Here, the authors propose a method to extract and separate exchange parameters in Kitaev materials, which can be applied to techniques such as inelastic neutron scattering and angle-dependent ferromagnetic resonance.