Effect of superconductivity on the shape of flat bands

Abstract For the first time, basing both on experimental facts and our theoretical consideration, we show that Fermi systems with flat bands should be tuned superconducting state. Experimental measurements magic-angle twisted bilayer graphene of velocity VF as a function temperature Tc superconduction phase transition have revealed ∝ 1⁄Ns(0), where Ns(0) is density states at level. We high-Tc compounds Bi2Sr2CaCu2O8+x exhibit same behavior. Such observation challenge to theories superconductivity, since VFis negatively correlated Tc, for 1⁄VF Ns(0). idea forming in strongly can explain this behavior other data collected graphene. Our findings place stringent constraints describing nature superconductivity deformation band by transition.