We demonstrate the impact of high-density calcium introduction into Ca-intercalated bilayer graphene on a SiC substrate, wherein a metallic layer of Ca has been identified at the interface. We have discerned that the additional Ca layer engenders a free-electron-like band, which subsequently hybridizes with a Dirac band, leading to the emergence of a van Hove singularity. Coinciding with this, there is an increase in the critical temperature for superconductivity. These findings allude to the manifestation of Ca-driven confinement epitaxy, augmenting superconductivity through the enhancement of attractive interactions in a pair of electron and hole bands with flat dispersion around the Fermi level.

中文翻译：

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限制外延诱导钙插层双层石墨烯的范霍夫奇点和增强超导性


我们证明了将高密度钙引入 SiC 基底上的 Ca 插层双层石墨烯中的影响，其中在界面处发现了 Ca 金属层。我们发现额外的 Ca 层会产生类似自由电子的能带，随后与狄拉克能带杂交，导致范霍夫奇点的出现。与此同时，超导临界温度也随之升高。这些发现暗示了钙驱动的限制外延的表现，通过增强费米能级周围平坦色散的一对电子和空穴带中的吸引力相互作用来增强超导性。