Quasi-1D XY antiferromagnet Sr 2 Ni(SeO 3 ) 2 Cl 2 at Sakai-Takahashi phase diagram.

Uniform quasi-one-dimensional integer spin compounds are of interest as a potential realization of the Haldane conjecture of a gapped spin liquid. This phase, however, has to compete with magnetic anisotropy and long-range ordered phases, the implementation of which depends on the ratio of interchain J' and intrachain J exchange interactions and both uniaxial D and rhombic E single-ion anisotropies. Strontium nickel selenite chloride, Sr ₂ Ni(SeO ₃ ) ₂ Cl ₂ , is a spin-1 chain system which passes through a correlations regime at T _max  ~ 12 K to long-range order at T _N  = 6 K. Under external magnetic field it experiences the sequence of spin-flop at B _c1  = 9.0 T and spin-flip transitions B _c2  = 23.7 T prior to full saturation at B _sat  = 31.0 T. Density functional theory provides values of the main exchange interactions and uniaxial anisotropy which corroborate the experimental findings. The values of J'/J = 0.083 and D/J = 0.357 place this compound into a hitherto unoccupied sector of the Sakai-Takahashi phase diagram.
(© 2021. The Author(s).)