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arXiv · 1301.0378

Plasmons dispersion and nonvertical interband transitions in single-crystal Bi2Se3 investigated by electron energy loss spectroscopy

S. C. Liou·M. -W. Chu·R. Sankar·F. -T. Huang·G. -J. Shu·F. C. Chou·C. H. Chen
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Abstract

Plasmons dispersion and nonvertical interband transitions in Bi2Se3 single crystals were investigated by electron energy-loss spectroscopy in conjunction with (scanning) transmission electron microscopy, (S)TEM-EELS. Both volume plasmons (π plasmon at 7 eV and π+σ plasmon at 17 eV) and surface plasmons (~5.5 and 10 eV) were demonstrated in STEM-EELS spectra and the corresponding spectral imaging in real space. In the further EELS experiments in reciprocal space, the momentum-dependent spectra reveal very different dispersion behavior between π and π+σ plasmons, with π+σ plasmons showing a typical quadratic dependence whereas the π plasmon exhibiting a linear dispersion analogous to what was reported for graphene. Furthermore, a low energy excitation 0.7~1.6 eV was also observed which is attributed to direct nonvertical interband transitions along the gamma-F direction.

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S. C. Liou, M. -W. Chu, R. Sankar, F. -T. Huang, G. -J. Shu, F. C. Chou, C. H. Chen. 2013-01-03. Plasmons dispersion and nonvertical interband transitions in single-crystal Bi2Se3 investigated by electron energy loss spectroscopy. https://doi.org/10.1103/physrevb.87.085126

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