Superconductivity-induced spectral weight transfer due to quantum geometry

Abstract

High-temperature superconductors show many phenomena that are not explained by the conventional Bardeen-Cooper-Schrieffer (BCS) theory. One such phenomenon in the cuprates is the superconductivityinduced transfer of the spectral weight from high to low energies whose scales differing by the order of two. While there are still debates on the origin of this phenomenon, a consensus is that it is due to strong correlation effects beyond the BCS theory. However, here we show that the presence of a nonzero spectral weight transfer does not require any kind of strong correlation physics. We show that the quantum geometry of the conduction band leads to a spectral weight transfer within the multi-band generalization of the BCS theory. We discuss applying this idea to twisted multilayer graphene.