Exciton energy-momentum map of hexagonal boron nitride

Giorgia Fugallo, Matteo Aramini, Jaakko Koskelo, Kenji Watanabe, Takashi Taniguchi, Mikko Hakala, Simo Huotari, Matteo Gatti, Francesco Sottile

Tutkimustuotos: ArtikkelijulkaisuArtikkeliTieteellinenvertaisarvioitu

Abstrakti

Understanding and controlling the way excitons propagate in solids is a key for tailoring materials with improved optoelectronic properties. A fundamental step in this direction is the determination of the exciton energy-momentum dispersion. Here, thanks to the solution of the parameter-free Bethe- Salpeter equation (BSE), we draw and explain the exciton energy-momentum map of hexagonal boron nitride (h-BN) in the first three Brillouin zones. We show that h-BN displays strong excitonic effects not only in the optical spectra at vanishing momentum $\mathbf{q}$, as previously reported, but also at large $\mathbf{q}$. We validate our theoretical predictions by assessing the calculated exciton map by means of an inelastic x-ray scattering (IXS) experiment. Moreover, we solve the discrepancies between previous experimental data and calculations, proving then that the BSE is highly accurate through the whole momentum range. Therefore, these results put forward the combination BSE and IXS as the tool of choice for addressing the exciton dynamics in complex materials.
Alkuperäiskieli englanti 165122 Physical Review B, Condensed Matter and Materials Physics 92 16 5 1098-0121 https://doi.org/10.1103/PhysRevB.92.165122 Julkaistu - 21 lokak. 2015 A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä, vertaisarvioitu

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