AI 中文总结
研究以单层FeSe/SrTiO3为模型，利用针尖诱导拉伸应变实现dz2带与dxy带的杂化，通过两级增强将超导能隙从17.8 meV扩至23.6 meV，确立了调控超导态的新途径。
AI 中文摘要
在铁基超导体中，dz2轨道带通常远低于费米能级，此前未被认为参与库珀对配对。本研究以单层FeSe/SrTiO3为模型体系，证明针尖诱导的 tensile 应变可可控地将dz2带移向费米能级，驱动超导性的两级增强：面内晶格膨胀首先增强电子关联，在初始阶段放大超导性；当应变进一步增大时，上移的dz2带与dxy带杂化，重构配对活性的d轨道带，引发第二次更强的能隙增强。这两个阶段共同将超导能隙从17.8 meV扩大至23.6 meV。整个过程中费米波矢保持不变，证实增强源于带重整化与重构而非载流子掺杂。本研究确立了通过应变激活电子关联与带工程调控超导态的途径，揭示了此前未被认识到的轨道选择性配对机制，对关联多带超导体具有广泛意义。
英文摘要
In iron-based superconductors, the dz2 orbital band typically resides far below the Fermi level and has not been considered to participate in Cooper pairing. Here, using monolayer FeSe/SrTiO3 as a model system, we demonstrate that tip-induced tensile strain controllably shifts the dz2 band toward the Fermi level, driving a two-stage enhancement of superconductivity. In-plane lattice expansion first enhances electronic correlation, amplifying superconductivity in the initial stage. As strain further increases, the upward-shifted dz2 band hybridizes with the dxy band, reconstructing the pairing-active d-orbital bands and inducing a secondary, stronger gap enhancement. Collectively, these two stages enlarge the superconducting gap from 17.8 to 23.6 meV. Throughout this process, invariant Fermi wave vectors confirm that the enhancement originates from band renormalization and reconstruction rather than carrier doping. Our work establishes a route to tailor superconducting states via strain-activated electronic correlations and band engineering, and reveals a previously unrecognized orbital-selective pairing mechanism with broad implications for correlated multiband superconductors.
Comments17 pages, 4 figures
Journal refProc. Natl. Acad. Sci. U.S.A. 123, e2602209123 (2026)
