Title: Modulation of the Octahedral Structure and Potential Superconductivity of La3Ni2O7 at Ambient Pressure by Compressive Strain

Abstract: Superconductivity at Tc = 80 K has recently been reported above 14 GPa in La3Ni2O7, which thus introduces a new family of high-temperature superconductors. Using a first-principles calculation with Coulomb repulsion, we unveil a surprising new route to obtain superconductivity in La3Ni2O7 at ambient pressure by introducing compressive strain along the [001] direction. The shape of the NiO6 octahedra affect the Ni-3dz2 density of states (DOS) at Fermi level, and it can be modulated by applying compressive strain instead of hydrostatic pressure. Notably, when the octahedral regularity parameter defined herein is R ~ 4%, La3Ni2O7 acquires a high Ni-3dz2 DOS and hole Fermi pocket. Our study thus indicates a path for obtaining superconductivity in La3Ni2O7 at ambient pressure and elucidates the relationship between structural properties and superconductivity.