The magnetic properties of one-dimensional spin-1 ferromagnetic Heisenberg model in a magnetic field within Callen approximation

The effect of magnetic field h on the magnetic properties of the one-dimensional spin-1 ferromagnetic Heisenberg model is studied by the double-time Green’s function method. The magnetization and susceptibility are obtained within the Callen approximation. The zero-field susceptibility is as a decreasing function of the temperature T . The magnetization m increases in the whole field region, but the susceptibility maximum χ ( T m ) decreases. The position T m of the susceptibility maximum is both solved analytically and fits well to be a power law T m ∼ h γ at low fields and to be linear increasing at high fields. The height χ ( T m ) decreases as a power law χ ( T m ) ∼ h − β with h increasing. The exponents ( γ , β ) obtained in our results agree with the other theoretical results. Our results are roughly in agreement with the results obtained in the experiment of Ni(OH)(NO3)H2O.