title: Correlation-length-exponent relation for the two-dimensional random ising model
abstract: We consider the two-dimensional (2D) random Ising model on a diagonal strip of the square lattice, where the bonds take two values, J1>J2, with equal probability. Using an iterative method, based on a successive application of the star-triangle transformation, we have determined at the bulk critical temperature the correlation length along the strip xi(L) for different widths of the strip L</=21. The ratio of the two lengths xi(L)/L=A is found to approach the universal value A=2/pi for large L, independent of the dilution parameter J(1)/J(2). With our method we have demonstrated with high numerical precision, that the surface correlation function of the 2D dilute Ising model is self-averaging, in the critical point conformally covariant and the corresponding decay exponent is eta( ||)=1.
authors.affiliation: Institute for Theoretical Physics, Szeged University, H-6720 Szeged, Hungary.
authors.initials: P
authors.lastname: Lajko
authors.initials: F
authors.lastname: Igloi