GROUND-STATE PROPERTIES OF THE (+/-)J ISING-MODEL IN 2 DIMENSIONS

We investigate the ground state properties of the ±J Ising model with asymmetric probability weight in two dimensions. We propose a numerical transfer matrix method which enables us to calculate directly the ground-state properties such as correlation functions, defect energy and entropy at T=0. We find that the spin glass correlation function decays in a power law like [formula omitted] with [formula omitted] in the range 0.5 ≤ p ≲ 0.85, suggesting the weak universality of spin glass–the concentration of +J bond is denoted by p. At the ferromagnetic phase boundary locating around p=0.89, the ferromagnetic correlation function decays as g(r)~r-η with η ≃ 0.240 ± 0.016, which suggests the weak universality of ferromagnetic critical exponent from the non-random critical point (p=1, T=2.269···) to the ground sate counterpart. The behavior of correlation functions, and also that of defect energies indicate the existence of an extra-phase, called the random antiphase state, in 0.85 ≲ p ≲ 0.89. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.