تقرير
Energy spectrum of two-dimensional excitons in a non-uniform dielectric medium
| العنوان: | Energy spectrum of two-dimensional excitons in a non-uniform dielectric medium |
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| المؤلفون: | Molas, M. R., Slobodeniuk, A. O., Nogajewski, K., Bartos, M., Bala, Ł., Babiński, A., Watanabe, K., Taniguchi, T., Faugeras, C., Potemski, M. |
| المصدر: | Phys. Rev. Lett. 123, 136801 (2019) |
| سنة النشر: | 2019 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Mesoscale and Nanoscale Physics |
| الوصف: | We demonstrate that, in monolayers (MLs) of semiconducting transition metal dichalcogenides, the $s$-type Rydberg series of excitonic states follows a simple energy ladder: $\epsilon_n=-Ry^*/(n+\delta)^2$, $n$=1,2,\ldots, in which $Ry^*$ is very close to the Rydberg energy scaled by the dielectric constant of the medium surrounding the ML and by the reduced effective electron-hole mass, whereas the ML polarizability is only accounted for by $\delta$. This is justified by the analysis of experimental data on excitonic resonances, as extracted from magneto-optical measurements of a high-quality WSe$_2$ ML encapsulated in hexagonal boron nitride (hBN), and well reproduced with an analytically solvable Schr\"odinger equation when approximating the electron-hole potential in the form of a modified Kratzer potential. Applying our convention to other, MoSe$_2$, WS$_2$, MoS$_2$ MLs encapsulated in hBN, we estimate an apparent magnitude of $\delta$ for each of the studied structures. Intriguingly, $\delta$ is found to be close to zero for WSe$_2$ as well as for MoS$_2$ monolayers, what implies that the energy ladder of excitonic states in these two-dimensional structures resembles that of Rydberg states of a three-dimensional hydrogen atom. Comment: Manuscript: 6 pages, 4 figures; SM: 11 pages, 12 figures |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1103/PhysRevLett.123.136801 |
| URL الوصول: | http://arxiv.org/abs/1902.03962 |
| رقم الأكسشن: | edsarx.1902.03962 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1103/PhysRevLett.123.136801 |
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