Signatures of Dimensionality and Symmetry in Exciton Band Structure: Consequences for Exciton Dynamics and Transport
| Autor: | Dana Novichkova, Diana Y. Qiu, Sivan Refaely-Abramson, Galit Cohen |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Physics
Condensed matter physics Scattering Mechanical Engineering Exciton Macroscopic quantum phenomena Electrons Bioengineering General Chemistry Classification of discontinuities Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Condensed Matter Physics Diffusion Condensed Matter::Materials Science symbols.namesake Ballistic conduction symbols Radiative transfer General Materials Science Hamiltonian (quantum mechanics) Electronic band structure |
| Zdroj: | Nano Letters. 21:7644-7650 |
| ISSN: | 1530-6992 1530-6984 |
| DOI: | 10.1021/acs.nanolett.1c02352 |
| Popis: | Exciton dynamics, lifetimes, and scattering are directly related to the exciton dispersion or band structure. Here, we present a general theory for exciton band structure within both ab initio and model Hamiltonian approaches. We show that contrary to common assumption, the exciton band structure contains nonanalytical discontinuities-a feature which is impossible to obtain from the electronic band structure alone. These discontinuities are purely quantum phenomena, arising from the exchange scattering of electron-hole pairs. We show that the degree of these discontinuities depends on materials' symmetry and dimensionality, with jump discontinuities occurring in 3D and different orders of removable discontinuities in 2D and 1D, whose details depend on the exciton degeneracy and material thickness. We connect these features to the early stages of exciton dynamics, radiative lifetimes, and diffusion constants, in good correspondence with recent experimental observations, revealing that the discontinuities in the band structure lead to ultrafast ballistic transport and suggesting that measured exciton diffusion and dynamics are influenced by the underlying exciton dispersion. |
| Databáze: | OpenAIRE |
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