MONTE-CARLO STUDY OF TOPOLOGICAL DEFECTS IN THE 3D HEISENBERG-MODEL

We use single-cluster Monte Carlo simulations to study the role of topological defects in the three-dimensional classical Heisenberg model on simple cubic lattices of size up to 80(3). By applying reweighting techniques to time series generated in the vicinity of the approximate infinite-volume transition point K(c), we obtain clear evidence that the temperature derivative of the average defect density d[n]/dT behaves qualitatively like the specific heat, i.e. both observables are finite in the infinite-volume limit. This is in contrast to results by Lau and Dasgupta who extrapolated a divergent behaviour of d[n]/dT at K(c) from simulations on lattices of size up to 16(3). We obtain weak evidence that d[n]/dT scales with the same critical exponent as the specific heat. As a byproduct of our simulations, we obtain a very accurate estimate for the ratio alpha/nu of the specific-heat exponent with the correlation-length exponent from a finite-size scaling analysis of the energy.