Magnetic excitation in buckled honeycomb compound gamma-Co2P2O7 with Kitaev magnetism

We propose to perform inelastic neutron scattering on buckled honeycomb compound gamma-Co2P2O7. Honeycomb cobaltates have been studied as a candidate of Kitaev spin liquid, but some of them have been shown to have predominant Heisenberg coupling, rather than Kitaev coupling, due to direct t2g hopping. To realize a Kitaev-dominant magnet, we focused on gamma-Co2P2O7 which has much larger Co-Co bond length than those of other honeycomb cobaltates, likely suppressing undesired Heisenberg coupling. gamma-Co2P2O7 shows two magnetic transitions at low temperatures. By increasing magnetic fields, the transitions are gradually suppressed and a spin-liquid-like behavior is seen above 7 T. However, we don't have detailed information about underlying magnetic interactions. We therefore plan to study the magnon dispersion by INS and extract relevant magnetic interactions.