Physical limitations of the Hohenberg–Mermin–Wagner theorem

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• Autor: Grgur Palle
• Autor: Denis Karl Sunko
• Autorova ustanova: Sveučilište u Zagrebu; Prirodoslovno-matematički fakultet; (Fizički odsjek)
• Znanstveno / umjetničko područje, polje i grana: PRIRODNE ZNANOSTI; Fizika

Sažetak (engleski)

The Hohenberg–Mermin–Wagner (HMW) theorem states that infrared (IR) fluctuations prevent long-range order which breaks continuous symmetries in two dimensions (2D), at finite temperatures. We note that the theorem becomes physically effective for superconductivity (SC) only for astronomical sample sizes, so it does not prevent 2D SC in practice. We systematically explore the sensitivity of the magnetic and SC versions of the theorem to finite-size and disorder effects. For magnetism, finite-size effects, disorder, and perpendicular coupling can all restore the order parameter at a non-negligible value of Tc equally well, making the physical reason for finite Tc sample-dependent. For SC, an alternative version of the HMW theorem is presented, in which the temperature cutoff is set by Cooper pairing, in place of the Fermi energy in the standard version. It still allows 2D SC at 2–3 times the room temperature when the interaction scale is large and Cooper pairs are small, the case with high-Tc SC in the cuprates. Thus IR fluctuations do not prevent 2D SC at room temperatures in samples of any reasonable size, by any known version of the HMW argument. A possible approach to derive mechanism-dependent upper bounds for SC Tc is pointed out.

• Ključne riječi (engleski): Mermin-Wagner theorem; infrared fluctuations; 2D systemssuperconductivity; disorder; finite-size effects
• Jezik: engleski
• Vrsta publikacije: Znanstveni rad - Izvorni znanstveni rad
• Status objave: Objavljen
• Vrsta recenzije: Recenziran - međunarodna recenzija
• Verzija publikacije: Objavljena verzija rada (izdavačev PDF)
• Naslov časopisa: Journal of Physics A: Mathematical and Theoretical
• Brojčani podaci: vol. 54, br. 31, 315001
• p-ISSN: 1751-8113
• e-ISSN: 1751-8121
• DOI: https://doi.org/10.1088/1751-8121/ac0a9d
• URN:NBN: urn:nbn:hr:217:896476
• Datum objave publikacije: 2021-07-01
• Projekt: Šifra: IP-2018-01-7828; Naziv (hrvatski): Sulfasoli: nova generacija kompleksnih funkcionalnih materijala; Naziv (engleski): Sulfosalts: new generation of complex fuctional materials; Kratica: SulfNewFunMat; Voditelj: Denis Sunko; Pravna nadležnost: Hrvatska; Financijer: Hrvatska zaklada za znanost; Linija financiranja: Research Projects
• URL dokumenta: https://iopscience.iop.org/article/10.1088/1751-8121/ac0a9d
• Vrsta resursa: Tekst
• Prava pristupa: Otvoreni pristup
• Javna napomena: © 2021 The Author(s). Published by IOP Publishing Ltd. Content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 24 February 2021. Revised 20 May 2021. Accepted for publication 11 June 2021. Published 1 July 2021.
• Datum i vrijeme pohrane: 2024-09-29 11:23:52