Flat-band superconductivity for tight-binding electrons on a square-octagon lattice

Lizardo H. C. M. Nunes; Cristiane Morais Smith

doi:10.1103/PhysRevB.101.224514

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Flat-band superconductivity for tight-binding electrons on a square-octagon lattice

Lizardo H. C. M. Nunes, Cristiane Morais Smith

DOI 10.1103/PhysRevB.101.224514 · Physical Review B

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Abstract

The discovery of superconductivity in twisted bilayer graphene has triggered a resurgence of interest in flat-band superconductivity. Here, we investigate the square-octagon lattice, which also exhibits two perfectly flat bands when next-nearest-neighbor hopping or an external magnetic field are added to the system. We calculate the superconducting phase diagram in the presence of on-site attractive interactions and find two superconducting domes, as observed in several types of unconventional superconductors. The critical temperature shows a linear dependence on the coupling constant, suggesting that superconductivity might reach high temperatures in the square-octagon lattice. Our model could be experimentally realized using photonic or ultracold atoms' lattices.