Abstract
Evidence for a Kosterlitz-Thouless transition in the two-dimensional (2D) step model is obtained from Monte Carlo determinations of the helicity modulus. It is argued that the free energy of a single vortex at the center of the system depends logarithmically on the system size in spite of the fact that the spin interaction is not harmonic for small differences in the spin angles. We conclude that this is the reason for the Kosterlitz-Thouless transition in the 2D step model and that the harmonic spin interaction not is a necessary requirement.
- Received 19 October 2000
DOI:https://doi.org/10.1103/PhysRevB.63.052407
©2001 American Physical Society