Self-consistent harmonic approximation in presence of non-local couplings

被引：8

作者：

Giachetti, Guido ^{[1
]}

Defenu, Nicolo ^{[2
]}

Ruffo, Stefano ^{[1
,4
]}

Trombettoni, Andrea ^{[1
,3
]}

机构：

[1] SISSA & INFN, Sez Trieste, Via Ronomea 265, I-34136 Trieste, Italy

[2] Swiss Fed Inst Technol, Inst Theoret Phys, Wolfgang Pauli Str 27, CH-8093 Zurich, Switzerland

[3] Univ Trieste, Dept Phys, Str Costiera 11, I-34151 Trieste, Italy

[4] CNR, Ist Sistemi Complessi, Via Madonna Piano 10, I-50019 Sesto Fiorentino, Italy

来源：

EPL | 2021年 / 133卷 / 05期

关键词：

LONG-RANGE ORDER; PHASE-TRANSITION; SUPERFLUID DENSITY; CRITICAL-BEHAVIOR; DYNAMICS; SYSTEMS; MODEL;

D O I：

10.1209/0295-5075/133/57004

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

We derive the self-consistent harmonic approximation for the 2D XY model with non-local interactions. The resulting equation for the variational couplings holds for any form of the spin-spin coupling as well as for any dimension. Our analysis is then specialized to power-law couplings decaying with the distance r as proportional to 1/r(2+sigma) in order to investigate the robustness, at finite sigma, of the Berezinskii-Kosterlitz-Thouless (BKT) transition, which occurs in the short-range limit sigma -> infinity. We propose an ansatz for the functional form of the variational couplings and show that for any sigma > 2 the BKT mechanism occurs. The present investigation provides an upper bound sigma* = 2 for the critical threshold sigma* above which the traditional BKT transition persists in spite of the non-local nature of the couplings. Copyright (C) 2021 EPLA

引用

页数：7

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