Quantum spin supersolid as a precursory Dirac spin liquid in a triangular lattice antiferromagnet

Abstract

Based on the recent experiments on the triangular lattice antiferromagnet Na_{2}BaCo(PO_{4})_{2}, we propose the easy-axis XXZ spin-1/2 model on the triangular lattice, that exhibits a quantum spin supersolid, to be a precursory Dirac spin liquid. Despite the presence of a three-sublattice magnetic order as a spin supersolid, we suggest that this system is close to a Dirac spin liquid by exploring its spectroscopic response. The physical consequence is examined from the spectroscopic response, and we establish the continuous spectra near the M point in addition to the K point excitation from the spinon continuum on top of the three-sublattice order. Moreover, the satellite peaks were predicted at the mid-points connecting the Γ and K points. This proposal offers a plausible understanding of the recent inelastic neutron scattering measurement in Na_{2}BaCo(PO_{4})_{2} and could inspire further research in relevant models and materials, such as K_{2}Co(SeO_{3})_{2} and Rb_{2}Co(SeO_{3})_{2}, and even more anisotropic magnets like PrMgAl_{11}O_{19}.