paper

Scaling Exponents in the Incommensurate Phase of the Sine-Gordon and U(1) Thirring Models

arXiv:cond-mat/0006422 · doi:10.1103/PhysRevB.63.085109

Abstract

In this paper we study the critical exponents of the quantum sine-Gordon and U(1) Thirring models in the incommensurate phase. This phase appears when the chemical potential exceeds a critical value and is characterized by a finite density of solitons. The low-energy sector of this phase is critical and is described by the Gaussian model (Tomonaga-Luttinger liquid) with the compactification radius dependent on the soliton density and the sine-Gordon model coupling constant . For a fixed value of , we find that the Luttinger parameter is equal to 1/2 at the commensurate-incommensurate transition point and approaches the asymptotic value away from it. We describe a possible phase diagram of the model consisting of an array of weakly coupled chains. The possible phases are Fermi liquid, Spin Density Wave, Spin-Peierls and Wigner crystal.

10pages; Improved version; Submitted to Physical Review B

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