AI 中文总结
研究重电子等离子体介导的可调谐超导性，通过随机相位近似和Eliashberg理论计算最小金属模型最优临界温度，发现适度声子吸引可提升临界温度，还考虑绝缘系统，提出相关平台，确立平带系统在超导性中可作可调谐配对介质的新角色。
AI 中文摘要
传统超导性的配对源自晶格振动，其特征尺度与化学和原子质量相关。等离子体（电子的集体振荡）可通过电子结构工程重塑，但最优等离子体介导配对的原理尚不明晰。本文为双载流子系统建立此类原理，重电子等离子体介导轻电子配对。在随机相位近似和Eliashberg理论下，计算最小金属模型的最优临界温度，表明其受等离子体能量尺度与延迟驱动的排斥抑制竞争控制，得出最优载流子密度和能带质量。仅等离子体通道时临界温度约0.1K，适度声子吸引可将其提升两个数量级至20K以上，但慢金属等离子体所需的能带扁平化也利于竞争序发展。因此考虑绝缘系统，其中平带间的相干带间跃迁产生无自由载流子的带隙带间等离子体。重带量子度量控制带间等离子体的色散和电子 - 等离子体配对强度，而轻带的量子几何抑制静态屏蔽并增强净吸引力。因层分离会迅速削弱配对，提出同一层不同镜面对称扇区中共存轻、重电子的系统作为有前景的平台。结果为重带系统在超导性中确立新角色：它们可作为可调谐配对介质，其集体电荷激发设定超导能量尺度，超越其窄带宽。
英文摘要
Conventional superconductivity derives its pairing glue from lattice vibrations, tying its characteristic scales to chemistry and atomic masses. Plasmons$-$the collective oscillations of electrons$-$can instead be reshaped through electronic structure engineering, but the principles governing optimal plasmon-mediated pairing remain unclear. Here, we establish such principles for two-carrier systems in which heavy-electron plasmons mediate the pairing of light electrons. Within the random-phase approximation and Eliashberg theory, we calculate the optimal $T_c$ of minimal metallic models and show that it is controlled by a competition between the plasmon energy scale and retardation-driven suppression of the repulsion, yielding optimal carrier densities and band masses. While the plasmon channel alone reaches only $T_c\sim$ 0.1 K, a moderate phonon attraction cooperates with it, boosting $T_c$ by two orders of magnitude to above 20 K. However, the band flattening needed for slow metallic plasmons also favors the development of competing orders. We therefore consider an insulating system in which coherent interband transitions between flat bands generate gapped interband plasmons without free carriers. The heavy-band quantum metric governs the dispersion and electron-plasmon pairing strength of the interband plasmon, while the quantum geometry of the light band suppresses static screening and enhances the net attraction. Because layer separation rapidly weakens pairing, we propose systems with coexisting light and heavy electrons living in different mirror-symmetry sectors of the same layer as promising platforms. Our results establish a new role for flat-band systems in superconductivity: rather than hosting the paired electrons themselves, they can serve as a tunable pairing mediator whose collective charge excitations set the superconducting energy scale beyond their narrow bandwidth.
Comments11 pages, 5 figures
