Competing Superconductivity and Electrostatic Fractionalization in non-Twisted Moiré Flat Bands

The quenching of the kinetic energy in electronic flat bands favors the emergence of highly correlated states, a phenomenon widely observed in recent years within moiré materials. These states have been extensively studied, particularly in twisted systems. However, from both theoretical and experimental perspectives, twisted materials present significant challenges. Here, we propose an alternative untwisted moiré system to circumvent these difficulties. This system reproduces many of the intriguing physical effects observed in moiré systems, such as flat bands and electron-electron pairing via a repulsive mechanism. The system consists of graphene subject to uniaxial periodic strain. By inducing a 1D moiré pattern through a mismatch between the honeycomb lattice and the strain, flat bands appear, corresponding to localized sub-lattice polarized states. By introducing a self-consistent Hartree interaction, we found a pinning of the van Hove singularities with the Fermi energy. Furthermore, competing correlated phases are obtained, such as superconductivity and symmetry-broken electrostatically fractionalized states.