TY - JOUR

T1 - Resonance Raman Scattering of Topological Insulators Bi2Te3 and Bi2 − xSbxTe3 − ySey Thin Films

AU - Kumar, N.

AU - Surovtsev, N. V.

AU - Ishchenko, D. V.

AU - Yunin, P. A.

AU - Milekhin, I. A.

AU - Tereshchenko, O. E.

AU - Milekhin, A. G.

N1 - This work was supported by the Russian Science Foundation (22-12-20024, p-9), the SRF SKIF Boreskov Institute of Catalysis (FWUR-2024-0042), and the Ministry of Science and Higher Education of Russia (FSUS-2024-0020).

PY - 2024/11/30

Y1 - 2024/11/30

N2 - Phonon occupation is temperature (T) dependent; it may participate in scattering with electronic states of topological insulators (TIs). Longitudinal optical (LO) phonons (Formula presented.) and (Formula presented.) in Bi2 − xSbxTe3 − ySey (BSTS) was resonantly excited by a photon energy (Ep) 2.33 eV due to electronic transition of unoccupied conduction band. The intensity of these modes was enhanced in Bi2Te3 film at Ep 1.87 eV, which is close to the electronic transition of unoccupied Dirac states. Fröhlich coupling strength was the main mechanism for higher intensity of (Formula presented.) and (Formula presented.) modes. At 300 K, the intensity of the (Formula presented.) mode was significantly decayed in both the BSTS and Bi2Te3 at Ep 2.33 and 1.87 eV due to the anharmonic coupling. However, at similar value of T, spectral profile of (Formula presented.) and (Formula presented.) modes was not affected because of the lower probability of decay rate of these phonons. In resonant condition, well-resolved Raman forbidden surface modes were observed at T of 50 K. At 300 K, more asymmetric Fano profile of surface phonon was observed due to the anharmonic coupling. The study indicated that at high T, (Formula presented.) mode and anharmonic coupling may become primary cause for scattering with electronic states of the TIs. However, at low T, primarily, both the LO phonons participated in the scattering.

AB - Phonon occupation is temperature (T) dependent; it may participate in scattering with electronic states of topological insulators (TIs). Longitudinal optical (LO) phonons (Formula presented.) and (Formula presented.) in Bi2 − xSbxTe3 − ySey (BSTS) was resonantly excited by a photon energy (Ep) 2.33 eV due to electronic transition of unoccupied conduction band. The intensity of these modes was enhanced in Bi2Te3 film at Ep 1.87 eV, which is close to the electronic transition of unoccupied Dirac states. Fröhlich coupling strength was the main mechanism for higher intensity of (Formula presented.) and (Formula presented.) modes. At 300 K, the intensity of the (Formula presented.) mode was significantly decayed in both the BSTS and Bi2Te3 at Ep 2.33 and 1.87 eV due to the anharmonic coupling. However, at similar value of T, spectral profile of (Formula presented.) and (Formula presented.) modes was not affected because of the lower probability of decay rate of these phonons. In resonant condition, well-resolved Raman forbidden surface modes were observed at T of 50 K. At 300 K, more asymmetric Fano profile of surface phonon was observed due to the anharmonic coupling. The study indicated that at high T, (Formula presented.) mode and anharmonic coupling may become primary cause for scattering with electronic states of the TIs. However, at low T, primarily, both the LO phonons participated in the scattering.

KW - Fröhlich strength

KW - Raman resonance

KW - anharmonic coupling

KW - polarization-resolved Raman spectroscopy

KW - topological insulators

UR - https://www.webofscience.com/wos/woscc/full-record/WOS:001362783900001

UR - https://www.mendeley.com/catalogue/a1991dda-fb4e-376b-bac9-b7b0d3340921/

U2 - 10.1002/jrs.6751

DO - 10.1002/jrs.6751

M3 - Article

JO - Journal of Raman Spectroscopy

JF - Journal of Raman Spectroscopy

SN - 0377-0486

ER -