Berezinskii-Kosterlitz-Thouless Paired Phase in Coupled XY Models

Year: 2019

Authors: Bighin G., Defenu N., Nandori I., Salasnich L., Trombettoni A.

Autors Affiliation: IST Austria, Campus 1, A-3400 Klosterneuburg, Austria; Heidelberg Univ, Inst Theoret Phys, D-69120 Heidelberg, Germany; MIA DE Particle Phys Res Grp, POB 51, H-4001 Debrecen, Hungary; MTA Atomki, POB 51, H-4001 Debrecen, Hungary; Univ Debrecen, POB 105, H-4010 Debrecen, Hungary; Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy; CNR, INO, Sez Sesto Fiorentino, Via Nello Carrara 2, I-50019 Sesto Fiorentino, Italy; CNR IOM DEMOCRITOS Simulat Ctr, Via Bonomea 265, I-34136 Trieste, Italy; SISSA, Via Bonornea 265, I-34136 Trieste, Italy; INFN, Sez Trieste, Via Bonornea 265, I-34136 Trieste, Italy

Abstract: We study the effect of a linear tunneling coupling between two-dimensional systems, each separately exhibiting the topological Berezinskii-Kosterlitz-Thouless (BKT) transition. In the uncoupled limit, there are two phases: one where the one-body correlation functions are algebraically decaying and the other with exponential decay. When the linear coupling is turned on, a third BKT-paired phase emerges, in which one body correlations are exponentially decaying, while two-body correlation functions exhibit power-law decay. We perform numerical simulations in the paradigmatic case of two coupled XY models at finite temperature, finding evidences that for any finite value of the interlayer coupling, the BKT-paired phase is present. We provide a picture of the phase diagram using a renormalization group approach.


Volume: 123 (10)      Pages from: 100601-1  to: 100601-6

DOI: 10.1103/PhysRevLett.123.100601

Citations: 5
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