AI 中文总结
研究Kek-α模型的等离激元特性，发现其因特殊电子结构导致稳定等离激元仅在小α或极小波矢时存在，该模型有望用于等离激元和纳米电子领域
AI 中文摘要
我们对Kek-α模型中的极化函数、等离激元激发及等离激元阻尼开展了严格的理论与数值研究，Kek-α模型是结合了α-T₃晶格与凯库勒畸变石墨烯关键特征的二维材料。与常规Kek-Y石墨烯不同，Kek-α模型中的凯库勒调制仅作用于两个子晶格中的一个，由此产生具有特殊电子性质的全新模型。其低能谱包含两条简并平带和两个不等价的狄拉克锥，费米速度不同，分别称为快锥与慢锥。导致朗道阻尼的粒子-空穴连续谱呈现两个不同分支，对应涉及这些狄拉克锥的跃迁；另一个粒子-空穴模式源于快狄拉克锥相关的电子跃迁，出现在主对角线上方。随着参数α增大，快狄拉克锥的贡献占主导；涉及平带与快狄拉克锥的额外跃迁大幅缩小了无阻尼等离激元的存在区域，与常规α-T₃模型类似。因此，仅在α值较小或波矢极小时可观测到稳定等离激元。这些特殊的电子与集体性质使Kek-α模型成为未来等离激元和纳米电子应用的有潜力平台。
英文摘要
We performed a rigorous theoretical and numerical investigation into the polarization function, plasmon excitations, and plasmon damping in the Kek-$α$ model, a two-dimensional material combining the key features of the $α-\mathcal{T}_3$ lattice and Kekule-distorted graphene. Unlike conventional Kek-Y graphene, the Kekule modulation in the Kek-$α$ model affects only one of the two sublattices, giving rise to a fundamentally new model with unusual electronic properties. The low-energy spectrum consists of two degenerate flat bands and two inequivalent Dirac cones with different Fermi velocities, referred to as the fast and slow cones. The particle-hole continuum responsible for Landau damping exhibits two distinct branches associated with transitions involving these Dirac cones. An additional particle-hole mode originates from electron transitions associated with the fast Dirac cone, appearing above the main diagonal. As the parameter $α$ increases, the contribution from the fast Dirac cone becomes dominant. The additional transitions involving the flat bands and the fast Dirac cone substantially reduce the region where undamped plasmons can exist, similarly to the conventional $α-\mathcal{T}_3$. Consequently, stable plasmons are observed only for relatively small values of $α$ or at very small wave vectors. These unusual electronic and collective properties make the Kek-$α$ model a promising platform for future plasmonic and nanoscale electronic applications.
Comments24 pages, 8 figures
