Physical review. B, Condensed matter
First-order transition in the XY model
H. J. F. Knops
Abstract
Recent Monte Carlo simulations suggest that changing the shape of the nearest-neighbor $\mathrm{XY}$ interaction might turn the infinite-order Kosterlitz-Thouless transition into a first-order one. In this Communication, an alternative explanation for the Monte Carlo data is proposed which is based on the renormalization pattern that results for this model in a Migdal-Kadanoff approximation.