RT info:eu-repo/semantics/article T1 Anisotropic excitonic effects in the energy loss function of hexagonal boron nitride A1 Serrano GutiƩrrez, Jorge AB The anisotropy of the valence energy-loss function of hexagonal boron nitride (hBN) is shown to be largely enhanced by the highly inhomogeneous character of the excitonic states. The energy loss with momentum transfer parallel to the BN layers is dominated by strongly bound, quasi-two-dimensional excitons. In contrast, excitations with momentum transfer perpendicular to the layers are influenced by weakly bound three-dimensional excitons. This striking phenomenon is revealed by a combined study using high-precision nonresonant inelastic x-ray scattering measurements supported by ab initio calculations. The results are relevant in general to layered insulating systems. PB American Physical Society YR 2011 FD 2011 LK https://uvadoc.uva.es/handle/10324/65241 UL https://uvadoc.uva.es/handle/10324/65241 LA eng NO Phys. Rev. B 83, 081413(R) (2011) DS UVaDOC RD 12-jul-2024