Ising Model for Ferromagnetism

Christopher M. Lemon, Ronald Johns

Gesualdo Delfino A, Giuseppe Mussardo

T. Morita

The boundary between the ferromagnetic and non-ferromagnetic phases is estimated by extrapolating the properties of finite systems, for the random-bond Ising model of the nearest-neighbour exchange integrals J>0 and -J with respective probabilities p and 1-p, on the square lattice.

Ulrich H. E. Hansmann

Taro Asano

It is shown that all the zeros of the partition function lie on the unit circle in the complex `fugacity' plane and the first inequality of Griffiths, Kelly and Sherman for the spin correlation functions also holds for the anisotropic Heisenberg ferromagnets as in the Ising model. The isotropic Heisenberg ferromagnets and the Ising ferromagnets are involved as special cases and thus the methods of this article provide alternative proof of the corresponding theorems in the Ising model.

J. A. Plascak