Crystal field excitations in a novel quantum spin liquid candidate

We propose to study the crystal field excitations in the quantum spin liquid candidate Na2BaCo(PO4)2. Here the material exhibits a number of interesting properties including the lack of magnetic orders yet a large magnetic entropy at low temperature, as well as strong low energy spin fluctuations resembling that of a spin-continuum, making this a potential candidate for a quantum spin liquid system. Nevertheless, the lack of an effective theoretical model makes it difficult to quantitatively describe the spin excitation spectrum measured by inelastic neutron scattering. We plan to carry out a mean-field and multilevel spin-orbit exciton calculation to model the spin system. For this purpose we would like to measure the crystal field excitations using single crystal Na2BaCo(PO4)2 samples to understand the crystal field contribution, which will be important in our model calculation.