Polarization dependence of coherent phonon generation and detection in the 3D topological insulator Bi2Te3

Abstract

We have studied the polarization dependence of coherent phonons in the topological insulator Bi2Te3. Using polarization-dependent femtosecond pump-probe spectroscopy, we measured coherent phonons as a function of angle when the pump and probe polarizations were fixed, and the crystal orientation was rotated. For isotropic detection, depending on the spot position, oscillations either from only low- and high-frequency phonons of A1g symmetry, or in addition from the mode at 3.6 THz were observed. All the modes were found to be independent of the orientation of electric field vector with respect to the crystal axes testifying to their full symmetry while no modes of lower symmetry appeared in any polarization geometry. For anisotropic detection both modes of Eg symmetry could be detected, but their amplitudes were considerably smaller than those of A1g symmetry. To clarify the coherent phonon assignment and the process of coherent phonon generation in Bi2Te3, the time-domain measurements were complemented by spontaneous Raman scattering. The comparison of frequency- and time-domain results and the polarization dependence suggest that the 3.6 THz mode belongs to crystalline Te arising due to tellurium segregation. A discrepancy between the time- and frequency domain data is discussed.

arXiv commentAccepted to Pysical Review RB, 27 pages, 11 figures

References in corpus (8)

• Two-Dimensional Gas of Massless Dirac Fermions in Graphene
• Topological Insulators
• Optical characterization of topological insulator surface states: Berry curvature-dependent response
• Topological quantization in units of the fine structure constant
• Distinguishing bulk and surface electron-phonon coupling in the topological insulator Bi2Se3 using time-resolved photoemission spectroscopy
• Generation of coherent phonons in bismuth by ultrashort laser pulses in the visible and NIR: displacive versus impulsive excitation mechanism
• Temperature-dependent chirped coherent phonon dynamics in Bi${}_2$Te${}_3$ using high intensity femtosecond laser pulses
• Fano Interference at the Excitation of Coherent Phonons: Relation between the Asymmetry Parameter and the Initial Phase of Coherent Oscillations

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• Ultrafast Quantum-path Interferometry Revealing the Generation Process of Coherent Phonons
• Femtosecond study of A1g phonons in the strong 3D topological insulators: From pump-probe to coherent control
• Observation of antiphase coherent phonons in the warped Dirac cone of Bi${}_2$Te${}_3$
• Coherent Dirac plasmons in topological insulators
• Surface Optical and Bulk Acoustic Phonons in the Topological Insulator, Bi2Se2Te
• Influence of local symmetry on lattice dynamics coupled to topological surface states
• A Microscopic Description of Displacive Coherent Phonons
• Ultrafast scattering dynamics of coherent phonons in Bi${}_{1-x}$Sb${}_x$ in the Weyl semimetal phase