Flat Bands and Giant Light-Matter Interaction in Hexagonal Boron Nitride
| Autor: | Abdelkarim Ouerghi, Pierre Valvin, James H. Edgar, Guillaume Cassabois, Christine Elias, Michele Lazzeri, Jianxiong Li, Christian Lhenoret, Bernard Gil, Giorgia Fugallo, Francesco Sottile |
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| Přispěvatelé: | Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Thermique et d’Energie de Nantes (LTeN), Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS), Kansas State University, Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de photonique et de nanostructures (LPN), Centre National de la Recherche Scientifique (CNRS), ANR-11-LABX-0014,GANEX,Réseau national sur GaN(2011), ANR-19-CE30-0007,BONASPES,Décrypter l'optique du h-BN en combinant des spectroscopies à haute résolution spatiale, énergétique et angulaire(2019), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS) |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Condensed matter physics Oscillator strength Exciton General Physics and Astronomy 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Brillouin zone Condensed Matter::Materials Science symbols.namesake Ab initio quantum chemistry methods 0103 physical sciences Density of states symbols Quantum efficiency Direct and indirect band gaps [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] van der Waals force 010306 general physics 0210 nano-technology |
| Zdroj: | Physical Review Letters Physical Review Letters, American Physical Society, 2021, 127 (13), pp.137401. ⟨10.1103/PhysRevLett.127.137401⟩ Physical Review Letters, 2021, 127 (13), pp.137401. ⟨10.1103/PhysRevLett.127.137401⟩ |
| ISSN: | 1079-7114 0031-9007 |
| DOI: | 10.1103/PhysRevLett.127.137401⟩ |
| Popis: | International audience; Dispersionless energy bands in k space are a peculiar property gathering increasing attention for the emergence of novel electronic, magnetic, and photonic properties. Here, we explore the impact of electronic flat bands on the light-matter interaction. The van der Waals interaction between the atomic layers of hexagonal boron nitride induces flat bands along specific lines of the Brillouin zone. The macroscopic degeneracy along these lines leads to van Hove singularities with divergent joint density of states, resulting in outstanding optical properties of the excitonic states. For the direct exciton, we report a giant oscillator strength with a longitudinal-transverse splitting of 420 meV, a record value, confirmed by our ab initio calculations. For the fundamental indirect exciton, flat bands result in phonon-assisted processes of exceptional efficiency, that compete with direct absorption in reflectivity, and that make the internal quantum efficiency close to values typical of direct band gap semiconductors. |
| Databáze: | OpenAIRE |
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