Acoustic phonon dynamics in thin-films of the topological insulator Bi2Se3

Abstract

Transient reflectivity traces measured for nanometer-sized films of the topological insulator Bi2Se3 revealed GHz-range oscillations driven within the relaxation of hot carriers photoexcited with ultrashort laser pulses of 1.51 eV photon energy. These oscillations have been suggested to result from acoustic phonon dynamics, including coherent longitudinal acoustic phonons in the form of standing acoustic waves. An increase of oscillation frequency from ~35 to ~70 GHz with decreasing film thickness from 40 to 15 nm was attributed to the interplay between two different regimes employing traveling-acoustic-waves for films thicker than 40 nm and the film bulk acoustic wave resonator (FBAWR) modes for films thinner than 40 nm. The amplitude of oscillations decays rapidly for films below 15 nm thick when the indirect intersurface coupling in Bi2Se3 films switches the FBAWR regime to that of the Lamb wave excitation. The frequency range of coherent longitudinal acoustic phonons is in good agreement with elastic properties of Bi2Se3.

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Cited by in corpus (18)

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• Anomalous Acoustic Plasmon Mode from Topologically Protected States
• Clarifying ultrafast carrier dynamics in ultrathin films of the topological insulator Bi2Se3 using transient absorption spectroscopy
• Nonlinear Optical Observation of Coherent Acoustic Dirac Plasmons in Thin-Film Topological Insulators
• Weakly Interacting Topological Insulators: Quantum Criticality and Renormalization Group Approach
• Revealing Optical Transitions and Carrier Recombination Dynamics within the Bulk Band Structure of Bi2Se3
• Plasmon-enhanced electron-phonon coupling in Dirac surface states of the thin-film topological insulator Bi2Se3
• Helicity dependent photovoltaic effect in Bi2Se3 under normal incident light
• THz Surface Modes and Electron-Phonon Coupling in Bi${}_2$Se${}_3$(111)
• Ultrafast carrier-lattice interactions and interlayer modulations of Bi2Se3 by X-ray free electron laser diffraction
• A supervised learning algorithm for interacting topological insulators based on local curvature
• Effect of Mn doping on ultrafast carrier dynamics in thin films of the topological insulator Bi2Se3
• Picosecond volume expansion drives a later-time insulator-metal transition in a nano-textured Mott Insulator
• Phase diagram and phonon-induced backscattering in topological insulator nanowires
• Multiphoton-pumped UV-Vis transient absorption spectroscopy of 2D materials: basic concepts and recent applications
• Nanosecond dynamics in intrinsic topological insulator ${\text{Bi}}_{2-x}{\text{Sb}}_x{\text{Se}}_3$ revealed by time-resolved optical reflectivity
• Two-photon IR pumped UV-Vis transient absorption spectroscopy of Dirac fermions in the 2D and 3D topological insulator Bi2Se3
• Ultrafast transient absorption spectroscopy of 2D semiconductors: a review