A Physical Realization of the Two-Dimensional Ising Model

Authors: Ch. MÜRSCH, U. RAMSPERGER, C.H. BACK, A. VATERLAUS, U. MAIR, D. PESCIA

Abstract: In 1925 E. Ising \cite{Ising} introduced the first and most elementary statistical model of a macroscopic system with short range interactions. This model - named after its inventor - was solved analytically for the non-trivial case of the interacting particles located on a two-dimensional (2d) lattice by Onsager \cite{Onsager} in 1944. This model and its solution provided the fundamental guidelines for all further theoretical developments in the theory of phase transitions. Despite the importance of the 2d-Ising model in Physics the experimental evidence gathered on it is scarce and incomplete, partly due to the very difficulty of realizing a truly 2d system in our three-coordinates world. In this paper, we describe a 2d system consisting of atomically thin films of magnetic Fe deposited onto a non-magnetic W-substrate. We show that Fe/W(110) near the magnetic critical point follows closely the predictions of the 2d-Ising model. In addition, we present a comprehensive confirmation of scaling and universality.

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