We systematically investigate the electronic structure, magnetism, and high-temperature superconductivity (SC) in multilayer octagraphene and octagraphite (bulk octagraphene). A tight-binding model is used to fit the electronic structures of single-layer and multilayer octagraphenes and octagraphite. We find that multilayer octagraphene and octagraphite follow a simple A-A stacking structure from the energy analysis. The van der Waals interaction induces $t_{\perp }\approx 0.25$ eV and the hopping integral within each layer changes little when the layer number $n$ increases. There is a well Fermi-surface nesting with nesting vector $\mathbf{Q}=(\pi ,\pi )$ for single-layer octagraphene at half-filling, which can induce a two-dimensional Néel antiferromagnetic order. With increasing layer number $n\to \infty$, the Fermi-surface nesting transforms to three-dimensional (3D) with nesting vector $\mathbf{Q}=(\pi ,\pi ,\pi )$ and shows that the system has a 3D Néel antiferromagnetic order. Upon doping, multilayer octagraphene and octagraphite can enter a high-temperature $s^{\pm }$ SC driven by spin fluctuation. We evaluate the superconducting transition temperature $T_c$ by using the random-phase approximation, which yields a high $T_c$ even if the layer number $n\ge 3$. Our study shows that multilayer octagraphene and octagraphite are promising candidates for realizing high-temperature SC.

中文翻译：

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多层八方石墨烯和八方石墨的电子结构，磁性和高温超导性

我们系统地研究了多层八方石墨烯和八方石墨烯（体八方石墨烯）中的电子结构，磁性和高温超导性（SC）。紧密结合模型用于拟合单层和多层八碳烯和八碳石的电子结构。我们从能量分析中发现，多层八碳烯和八碳石遵循简单的AA堆叠结构。范德华相互作用引起${Ť}_{\perp }\approx 0.25$ 当层数增加时，每层的eV和跳跃积分变化不大 $ñ$增加。有一个带有嵌套向量的费米曲面嵌套$\mathbf{问}=（\pi ，\pi ）$单层八碳烯在半填充时会产生二维Néel反铁磁序。随着层数的增加$ñ\to \infty$，费米曲面嵌套使用嵌套矢量转换为三维（3D） $\mathbf{问}=（\pi ，\pi ，\pi ）$并显示该系统具有3DNéel反铁磁顺序。掺杂后，多层八碳烯和八碳石会进入高温$s^{\pm }$SC由自旋波动驱动。我们评估超导转变温度${Ť}_C$ 通过使用随机相位近似，可以得到很高的 ${Ť}_C$ 即使层号 $ñ\ge 3$。我们的研究表明，多层八碳烯和八碳石是实现高温SC的有希望的候选物。