Thermodynamic properties of a spin-1 tetrahedron as a model for a molecule-based compound [Mo12O30(μ2-OH)10H2{Ni (H2O)3}4]·14H2O

The magnetic and thermodynamic properties of the spin-1 tetrahedral “Ni4” model have been investigated in terms of the Heisenberg model by algebraic method. It is shown that the Heisenberg model provides an adequate description of the magnetization at low temperatures. The temperature dependence of the specific heat of this model in the vicinity of the midpoint at the rising magnetization M shows remarkable double-peak structure due to the ferromagnetic gapless and anti-ferromagnetic gap excitation of the spin system. The magnetization curve has four clear plateaus, and the susceptibilities exhibit typical anti-ferromagnetic feature, which is well consistent with experimental findings. In particular, the critical magnetic field values H1=5.40 T, H2=10.69 T, H3=16.05 T and H4=28.06 T corresponding to the magnetization plateaus are in quantitative agreement with the experimental observations and the former theoretical calculation.