Coulomb interaction in monolayer transition-metal dichalcogenides
Coulomb interaction in monolayer transition-metal dichalcogenides
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DOI：
10.1103/physrevb.98.125308
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发表时间：
2018-09-27
影响因子：
3.7
通讯作者：
Dery, Hanan
中科院分区：
文献类型：
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作者：
Dinh Van Tuan;Yang, Min;Dery, Hanan
近年来，著名的Rytova-Keldysh势被广泛用于描述单层过渡金属二硫属化合物中少体配合物的库仑相互作用。使用这种潜在的模型带电激子（trions），人们发现一个强烈的依赖于单层是否悬浮在空气中，支持SiO2，或封装在六方氮化硼的结合能。然而，三振子结合能的经验值显示弱依赖于单层配置。这一缺陷表明，库仑势的描述仍然缺乏这类重要的材料。我们解决这个问题，并得出一个新的潜在的形式，它考虑到三个原子片，构成一个单层的过渡金属dichalcogenides。新势自洽地支持（i）中性激子的非氢Rydberg系列和（ii）trion结合能对环境的弱依赖性。此外，我们确定了一个重要的trion晶格耦合由于声子云附近的带电复合物。另一方面，处于基态的中性激子由于其电荷中性和小玻尔半径的汇合而具有较弱的晶格耦合。
Recently, the celebrated Rytova-Keldysh potential has been widely used to describe the Coulomb interaction of few-body complexes in monolayer transition-metal dichalcogenides. Using this potential to model charged excitons (trions), one finds a strong dependence of the binding energy on whether the monolayer is suspended in air, supported on SiO2, or encapsulated in hexagonal boron-nitride. However, empirical values of the trion binding energies show weak dependence on the monolayer configuration. This deficiency indicates that the description of the Coulomb potential is still lacking in this important class of materials. We address this problem and derive a new potential form, which takes into account the three atomic sheets that compose a monolayer of transition-metal dichalcogenides. The new potential self-consistently supports (i) the nonhydrogenic Rydberg series of neutral excitons and (ii) the weak dependence of the trion binding energy on the environment. Furthermore, we identify an important trion-lattice coupling due to the phonon cloud in the vicinity of charged complexes. Neutral excitons in their ground state, on the other hand, have weaker coupling to the lattice due to the confluence of their charge neutrality and small Bohr radius.