二维材料中激子、声子和等离子体激元色散的统一描述：基于光学电导率近似
Unified description of exciton, phonon and plasmon dispersions in 2D materials from an optical conductivity approximation
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中文总结 AI 辅助
本文提出光学电导率近似（OCA）统一框架，仅用q=0光学电导率描述二维材料中激子、声子和等离子体激元的线性色散，并在hBN和石墨烯上准确重现实验色散，提供高效计算低动量EELS数据的方案。
中文摘要 AI 辅助
二维（2D）材料中修正的库仑相互作用导致激子、声子和等离子体激元具有独特的非解析低动量色散。在此，我们通过引入光学电导率近似（OCA）来描述二维纵向激发的色散，该统一框架仅利用q=0的光学电导率即可评估电子能量损失谱（q-EELS）所探测的有限q纵向响应。通过这种方式，该方法表明上述所有激发的线性色散主要源于二维宏观库仑相互作用的形式，而非底层能带结构的色散。将该方法应用于六方氮化硼和石墨烯，我们准确重现了hBN纵向光学声子和低能亮激子以及石墨烯π等离子体激元的能量和强度色散。我们的工作还提供了一种高效的计算方案，无需在密集动量点计算响应函数即可描述低动量EELS数据。
英文摘要
The modified Coulomb interaction in two-dimensional (2D) materials gives rise to unique, non-analytic low-momentum dispersions of excitons, phonons, and plasmons. Here, we describe the 2D dispersion of longitudinal excitations by introducing the optical conductivity approximation (OCA), a unified framework that evaluates the finite-q longitudinal response probed by electron energy-loss spectroscopy (q-EELS) by only using the q = 0 optical conductivity. By doing so, the approach demonstrates that the linear dispersion of all the above mentioned excitations is mainly due to the form of the 2D macroscopic Coulomb interaction rather than to the dispersion of the underlying band structure. Applying this approach to hexagonal boron nitride and graphene we accurately reproduce the energy and intensity dispersions of the hBN longitudinal-optical phonon and low-energy bright excitons, along with the graphene pi-plasmon. Our work also provides an efficient computational scheme to describe low momentum EELS data without the need to calculate the response functions at dense moment
发表机构
- Università di Roma La Sapienza（罗马第一大学）
- Istituto Nanoscienze – CNR, S3（意大利国家研究委员会纳米科学研究所）
- CNR-SPIN（意大利国家研究委员会自旋物理研究所）
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