论文标题
二维狄拉克材料中的激子振荡器强度
Exciton oscillator strength in two-dimensional Dirac materials
论文作者
论文摘要
激子问题在二维DIRAC模型中解决了，具有强烈的电子孔吸引力。假定激子结合能比带隙要小但可以媲美。在动量空间中发现了激子函数，作为所有四个两个粒子状态的叠加，包括电子和孔状态，具有正能和负能。激子生成的矩阵元素被证明取决于激子函数的其他成分。都考虑了库仑和rytova-keldysh电位。分析了地面和首次激发激发态态的结合能对耦合常数的依赖性。研究了实际过渡金属二进制基因元素单层的结合能和振荡器强度作为环境依赖性介电常数的功能。我们证明，激子波函数的多组分性质对于描述二维狄拉克系统的共振光学性质至关重要。
Exciton problem is solved in the two-dimensional Dirac model with allowance for strong electron-hole attraction. The exciton binding energy is assumed smaller than but comparable to the band gap. The exciton wavefunction is found in the momentum space as a superposition of all four two-particle states including electron and hole states with both positive and negative energies. The matrix element of exciton generation is shown to depend on the additional components of the exciton wavefunction. Both the Coulomb and the Rytova-Keldysh potentials are considered. The dependence of the binding energy on the coupling constant is analyzed for the ground and first excited exciton states. The binding energy and the oscillator strength are studied as functions of the environmental-dependent dielectric constant for real transition metal dichalcogenide monolayers. We demonstrate that the multicomponent nature of the exciton wavefunction is crucial for description of resonant optical properties of two-dimensional Dirac systems.
