Low Temperature Physics

Effect of an external field on the thermodynamics of the free-fermion model

S. B. Rutkevich

Published Dec 1, 1993• 0 citations

Abstract

The effect of an external field on the phase transition is studied in the continuous version of the model of free fermions without dislocations. The critical indices δ = ∞, β = + 0, γ = 3/2 and the phase diagram are obtained as well as an exact expression for the free energy in the strong field limit. The results are compared with scaling properties in the six-vertex model. While the similarity of scaling in zero field and a coincidence of the values of β and δ indicate that both models have the same class of universality, considerable differences are observed in other characteristics like the index γ, phase diagram, and scaling function. This “discrepancy” is explained by the fact that the external field violates the symmetry in fermion and six-vertex models in different ways. The possibility of experimental observation of the obtained scaling dependences in two-dimensional crystals undergoing a transition to the incommensurate phase is discussed.

DOI: 10.1063/10.0033556

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