Plasmons dispersion and nonvertical interband transitions in single crystal Bi2Se3investigated 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
2013 Physical Review B  
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
more » ... veal 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.
doi:10.1103/physrevb.87.085126 fatcat:gxaz76wvdfakdaz2nuxuw4lkxu