标题： 倒置不对称性对双层石墨烯超导和激子凝聚的影响 显示英文标题

标题： Effect of Inversion Asymmetry on Bilayer Graphene's Superconducting and Exciton Condensates

摘要： 双层石墨烯中的反演不对称性可以通过位移场进行调节。 因此，偏置双层石墨烯中的能带色散在狄拉克点附近呈现出平带区域，并伴随非平凡的能带几何结构。 我们分析了反演对AB堆叠石墨烯双层超导态临界温度和超流刚度以及由两个AB堆叠石墨烯双层形成的双层中激子凝聚的影响。 发现双层石墨烯超导体中的几何超流刚度由于超导能隙较小而可以忽略不计。 此外，我们表明几何超流刚度在常数序参量下达到最大值。 因此，在具有任何配对对称性的偏置双层石墨烯超导体中可以忽略不计。 然而，位移场增强了激子凝聚中的几何超流刚度。 在低密度和高位移场时最为显著。 几何超流刚度的一个结果是双层石墨烯激子凝聚中的贝瑞辛斯基-科斯特里茨-索利斯转变温度适度提高。 显示英文摘要

摘要： Inversion asymmetry in bilayer graphene can be tuned by the displacement field. As a result, the band dispersion in biased bilayer graphene acquires flat band regions near the Dirac points along with a non-trivial band geometry. We analyze the effect of inversion symmetry on the critical temperature and superfluid stiffness of the superconducting state of AB-stacked graphene bilayer and on the exciton condensate in double layers formed by two AB-stacked graphene bilayers. The geometric superfluid stiffness in bilayer graphene superconductors is found to be negligible due to the small superconducting gap. Furthermore, we show that the geometric superfluid stiffness is maximized for a constant order parameter. Therefore, it can be neglected in biased bilayer graphene superconductors with any pairing symmetry. However, the displacement field enhances the geometric superfluid stiffness in exciton condensates. It is most prominent at low densities and high displacement fields. A consequence of the geometric superfluid stiffness is a modest enhancement of the Berezinskii-Kosterlitz-Thouless transition temperature in bilayer graphene's exciton condensate.