Superfluid weight cross-over and critical temperature enhancement in singular flat bands

• 成果类型: Article
• 署名作者: Jiang, Guodong; Torma, Paivi; Barlas, Yafis
• 署名单位: Nevada System of Higher Education (NSHE); University of Nevada Reno; Aalto University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8516
• DOI: 10.1073/pnas.2416726122
• 发表日期: 2025-02-18
• 关键词: superconductivity

摘要

Nonanalytic Bloch eigenstates at isolated band degeneracy points exhibit singular behavior in the quantum metric. Here, a description of superfluid weight for zero- energy flat bands in proximity to other high-energy bands is presented, where they together form a singular band gap system. When the singular band gap closes, the geometric and conventional contributions to the superfluid weight as a function of the superconducting gap exhibit different cross-over behaviors. The scaling behavior of superfluid weight with the band gap is studied in detail, and the effect on the Berezinskii-Kosterlitz-Thouless transition temperature is explored. It is found that tuning the singular band gap provides a unique mechanism for enhancing the supercurrent and critical temperature of two-dimensional superconductors.