Magnetic Susceptibility in the Ising Model

Tuncer Kaya

David L. Huber, T. N. Tommet

Oleg A. Vasilyev, Щур Лев Николаевич

The behavior of the magnetic susceptibility of a two-dimensional Ising model with nonmagnetic impurities is investigated numerically. A new method for determining the critical amplitudes and critical temperature is developed. The results of a numerical investigation of the ratio of the critical amplitudes of the magnetic susceptibility are presented. It is shown that the ratio of the critical amplitudes is universal right up to impurity concentrations q ≤ 0.25 (the percolation point of a square lattice is q c = 0.407254). The behavior of the effective critical exponent γ( q ) of the magnetic susceptibility is discussed. Apparently, a transition from Ising-type universal behavior to percolation behavior should occur in a quite narrow concentration range near the percolation point of the lattice.

Eytan Barouch, Barry M. McCoy

We study the 1‐ dimensional Ising model with random coupling constants in the presence of a transverse magnetic field h. In the nonrandom (translationally invariant) case it is known that there is a value of h for which the magnetic susceptibility diverges logarithmically. We demonstrate that in the random case this logarithmic divergence is smoothed out into an infinitely differentiable essential singularity.

M F Sykes, Michael Ellis Fisher

А. А. Бабаев, Akai Kurbanovich Murtazaev