{"title":"Quantum Monte Carlo calculation of critical temperature of flat-band superconductivity in the Lieb-lattice Hubbard model","authors":"Jicheol Kim, Dong-Hee Kim","doi":"10.1007/s40042-026-01663-z","DOIUrl":null,"url":null,"abstract":"<div><p>We investigate a superconducting transition in the attractive Hubbard model on the Lieb lattice at the half-filled flat band with linear band-touching. Using the determinant quantum Monte Carlo simulations, we estimate the Berezinskii–Kosterlitz–Thouless (BKT) transition temperature for the onsite interaction <span>\\(|U|=1\\)</span> based on the universal relation with the superfluid weight. We also perform a finite-size scaling analysis of the pair-field structure factor, examining its consistency with the BKT transition. Our estimate of the transition temperature <span>\\(T_c \\approx 0.032\\)</span> exhibits notable differences from previous static and dynamical mean-field estimates, implying a significant role of quantum fluctuations near the onset of superconductivity in this gapless flat-band system.</p></div>","PeriodicalId":677,"journal":{"name":"Journal of the Korean Physical Society","volume":"89 6","pages":"639 - 644"},"PeriodicalIF":1.0000,"publicationDate":"2026-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the Korean Physical Society","FirstCategoryId":"101","ListUrlMain":"https://link.springer.com/article/10.1007/s40042-026-01663-z","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"PHYSICS, MULTIDISCIPLINARY","Score":null,"Total":0}
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Abstract
We investigate a superconducting transition in the attractive Hubbard model on the Lieb lattice at the half-filled flat band with linear band-touching. Using the determinant quantum Monte Carlo simulations, we estimate the Berezinskii–Kosterlitz–Thouless (BKT) transition temperature for the onsite interaction \(|U|=1\) based on the universal relation with the superfluid weight. We also perform a finite-size scaling analysis of the pair-field structure factor, examining its consistency with the BKT transition. Our estimate of the transition temperature \(T_c \approx 0.032\) exhibits notable differences from previous static and dynamical mean-field estimates, implying a significant role of quantum fluctuations near the onset of superconductivity in this gapless flat-band system.
期刊介绍：
The Journal of the Korean Physical Society (JKPS) covers all fields of physics spanning from statistical physics and condensed matter physics to particle physics. The manuscript to be published in JKPS is required to hold the originality, significance, and recent completeness. The journal is composed of Full paper, Letters, and Brief sections. In addition, featured articles with outstanding results are selected by the Editorial board and introduced in the online version. For emphasis on aspect of international journal, several world-distinguished researchers join the Editorial board. High quality of papers may be express-published when it is recommended or requested.
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