Test of scaling in two dimensions

The purpose of this paper is to report on the first comprehensive experimental test of the scaling hypothesis in two-dimensional physics. This hypothesis predicts that the equation of state near a phase transition of a system in thermodynamic equilibrium obeys a simple scaling law. Our experimental data, obtained on a truly two-dimensional magnetic system consisting of a subnanometer thick Fe films grown on top of a non-magnetic surface, explicitly display scaling. The experimental evidence suggests that this system is an almost perfect realization of a 2d Ising model.