Spectroscopy of condensed matter

Changes in the optical functions of a Bi$_{0.6}$Sb$_{1.4}$Te$_3$ crystal when the plasmon and electronic transition

N. P. Stepanov<sup>ab

a</sup> Zabaikalsky State University, 672036 Chita, Russia
^b Baikal State University, 664003 Irkutsk, Russia

Abstract: During the study of the reflection spectra of the Bi$_{0.6}$Sb$_{1.4}$Te$_3$ crystal, a deformation of the plasma edge was detected, which increases with a decrease in temperature. The analysis of the behavior of optical functions calculated from the reflection spectra using the Kramers–Kronig relations suggests that there is a convergence of the energies of the plasmon $E_p$ and the electron transition between the nonequivalent extremes of the valence band $\Delta E$, accompanied by an increase in the electron-plasmon interaction. The changes in the real and imaginary parts of the permittivity function, as well as the energy loss functions occurring during the convergence of $E_p$ and $\Delta E$ are described. It is established that the convergence of $E_p$ and $\Delta E$ leads to the splitting of the peak of the energy loss function into two maxima, the spectral position of which does not change with a decrease in temperature from 101 to 78 K.

Keywords: reflection spectra, optical functions, plasma oscillations, electronic transitions, electron-plasmon interaction.

Received: 27.05.2023
Revised: 28.09.2023
Accepted: 29.09.2023

DOI: 10.61011/OS.2023.09.56608.5264-23

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