Data for Magnetic properties of a staggered S = 1 chain with an alternating single-ion anisotropy direction

While theoretical and experimental studies have extended this model to include various other energy scales, the effect of the lack of a common SIA axis is not well explored. Here we investigate the magnetic properties of Ni(pyrimidine)(H2O)2(NO3)2, a chain compound where the tilting of Ni octahedra leads to a 2-fold alternation of the easy-axis directions along the chain.

Muon-spin relaxation measurements indicate a transition to long-range order at TN = 2.3K and the magnetic structure is initially determined to be antiferromagnetic and collinear using elastic neutron diffraction experiments. Inelastic neutron scattering measurements were used to find J0 = 5.107(7) K, D = 2.79(1) K, J′2 = 0.18(3)K and a rhombic anisotropy energy E = 0.19(9) K. Mean-field modelling reveals that the ground state structure hosts spin canting of ϕ ≈ 6.5◦, which is not detectable above the noise floor of the elastic neutron diffraction data.