Neutron diffraction studies of the magnetic phase diagram of the effective spin-1/2 triangular lattice antiferromagnet Na₂BaCo(PO₄)₂

We report single crystal time-of-flight neutron diffraction measurements as function of applied magnetic field in the effective spin-1/2 stacked triangular lattice antiferromagnet Na₂BaCo(PO₄)₂, recently proposed as a candidate to display unconventional magnetic behaviour with a rich phase diagram in applied c-axis field including a 1/3rd magnetization plateau phase [1,2]. We characterize the magnetic diffraction pattern in the various phases and discuss models of the magnetic structure evolution as a function of applied magnetic field up to saturation. [1] R.D. Zhong et al, Proc. Natl Acad. Sci. USA 116, 14505 (2019). [2] N. Li et al. Nat. Commun. 11, 1-9 (2020).