Electronic structure, magnetism and high-temperature superconductivity in the multi-layer octagraphene and octagraphite
Abstract
We systematically investigate the electronic structure, magnetism and high-temperature superconductivity (SC) in the multi-layer octagraphene and octagraphite (bulk octagraphene). A tight binding model is used to fit the electronic structures of single-layer, multi-layer octagraphenes and octagraphite. We find that the multi-layer octagraphene and octagraphite follow a simple A-A stacking structure from the energy analysis. The van der Waals interaction induces t≈0.25 eV and the hopping integrals within each layers changes little when the layer number n increases. There is a well Fermi-surface nesting with nesting vector Q=(π,π) for the single-layer octagraphene at half-filling, which can induce a 2D N\'eel antiferromagnetic order. With increasing the layer number n→∞, the Fermi-surface nesting transforms to 3D with nesting vector Q=(π,π,π) and shows the system has a 3D N\'eel antiferromagnetic order. Upon doping, the multi-layer octagraphene and octagraphite can enter a high-temperature s SC driven by spin fluctuation. We evaluate the superconducting transition temperature Tc by using the random-phase approximation (RPA), which yields a high Tc even if the layer number n≥ 3. Our study shows that the multi-layer octagraphene and octagraphite are promising candidates for realizing the high-temperature SC.