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 chi (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 similar to h(gamma) at low fields and to be linear increasing at high fields. The height chi (T-m) decreases as a power law chi (T-m) similar to h(-beta) with h increasing. The exponents (gamma, beta) 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. (C) 2011 Published by Elsevier Ltd