Monte Carlo evidence for the absence of a phase transition in the two-dimensional Ising spin glass

Abstract

Monte Carlo calculations have been performed for an Ising system on a square lattice with nearest-neighbour interactions distributed according to a Gaussian with zero mean. The susceptibility is computed from the time averages of the fluctuating magnetisation and its square, and exhibits the characteristic maximum as a function of temperature. The height and position of this peak are found to depend on the 'observation time' used for the computation of the time averages. This is interpreted as evidence for the absence of a phase transition.