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arXiv · 1005.0930

Anisotropic excitonic effects in the energy loss function of hexagonal boron nitride

S. Galambosi·L. Wirtz·J. A. Soininen·J. Serrano·A. Marini·K. Watanabe·T. Taniguchi·S. Huotari·A. Rubio·K. Hämäläinen
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Abstract

We demonstrate that the valence energy-loss function of hexagonal boron nitride (hBN) displays a strong anisotropy in shape, excitation energy and dispersion for momentum transfer q parallel or perpendicular to the hBN layers. This is manifested by e.g. an energy shift of 0.7 eV that cannot be captured by single-particle approaches and is a demonstration of a strong anisotropy in the two-body electron-hole interaction. Furthermore, for in-plane directions of q we observe a splitting of the -plasmon in the M direction that is absent in the K direction and this can be traced back to band-structure effects.

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S. Galambosi, L. Wirtz, J. A. Soininen, J. Serrano, A. Marini, K. Watanabe, T. Taniguchi, S. Huotari, A. Rubio, K. Hämäläinen. 2010-05-06. Anisotropic excitonic effects in the energy loss function of hexagonal boron nitride. https://doi.org/10.1103/physrevb.83.081413

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