Khasanov Rustem, Ruan Bin-Bin, Shi Yun-Qing, Chen Gen-Fu, Luetkens Hubertus, Ren Zhi-An, Guguchia Zurab
Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232, Villigen PSI, Switzerland.
Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, 100190, Beijing, China.
Nat Commun. 2024 Mar 11;15(1):2197. doi: 10.1038/s41467-024-46514-2.
The superconductivity in systems containing dispersionless (flat) bands is seemingly paradoxical, as traditional Bardeen-Cooper-Schrieffer theory requires an infinite enhancement of the carrier masses. However, the combination of flat and steep (dispersive) bands within the multiple band scenario might boost superconducting responses, potentially explaining high-temperature superconductivity in cuprates and metal hydrides. Here, we report on the magnetic penetration depths, the upper critical field, and the specific heat measurements, together with the first-principles calculations for the MoSiP superconducting family. The band structure features a flat band that gradually approaches the Fermi level as a function of phosphorus doping x, reaching the Fermi level at x ≃ 1.3. This leads to an abrupt change in nearly all superconducting quantities. The superfluid density data placed on the 'Uemura plot' results in two separated branches, thus indicating that the emergence of a flat band enhances correlations between conducting electrons.
在包含无色散（平坦）能带的体系中，超导现象看似自相矛盾，因为传统的巴丁 - 库珀 - 施里弗理论要求载流子质量无限增强。然而，在多能带情形下，平坦能带与陡峭（色散）能带的结合可能会增强超导响应，这有可能解释铜酸盐和金属氢化物中的高温超导现象。在此，我们报告了对MoSiP超导家族的磁穿透深度、上临界场和比热的测量结果，以及第一性原理计算。能带结构的特征是一个平坦能带，它随着磷掺杂量x逐渐接近费米能级，在x≃1.3时达到费米能级。这导致几乎所有超导量都发生突然变化。置于“上村图”上的超流密度数据产生了两个分离的分支，因此表明平坦能带的出现增强了传导电子之间的相关性。
