Spatially resolved femtosecond pump-probe study of topological insulator Bi2Se3

Abstract

Carrier and phonon dynamics in Bi2Se3 crystals are studied by a spatially resolved ultrafast pump-probe technique. Pronounced oscillations in differential reflection are observed with two distinct frequencies, and are attributed to coherent optical and acoustic phonons, respectively. The rising time of the signal indicates that the thermalization and energy relaxation of hot carriers are both sub-ps in this material. We found that the thermalization and relaxation time decreases with the carrier density. The expansion of the differential reflection profile allows us to estimate an ambipolar carrier diffusion coefficient on the order of 500 square centimeters per second. A long-term slow expansion of the profile shows a thermal diffusion coefficient of 1.2 square centimeters per second.

arXiv comment8 pages, 6 figures

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• Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3
• Measurement of intrinsic Dirac fermion cooling on the surface of a topological insulator Bi${}_2$Se${}_3$ using time- and angle-resolved photoemission spectroscopy
• Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi${}_2$Se${}_3$
• Distinguishing bulk and surface electron-phonon coupling in the topological insulator Bi2Se3 using time-resolved photoemission spectroscopy
• Ultrafast carrier dynamics in thin-films of the topological insulator Bi2Se3
• Ultrafast Electron Dynamics in the Topological Insulator Bi2Se3 Studied by Time-Resolved Photoemission Spectroscopy
• Viscoelastic response of topological tight-binding models in two and three dimensions
• Time-resolved terahertz dynamics in thin films of the topological insulator Bi${}_2$Se${}_3$
• Unraveling photoinduced spin dynamics in topological insulator Bi2Se3
• Effect of carrier recombination on ultrafast carrier dynamics in thin films of the topological insulator Bi2Se3
• Coherent control of injection currents in high-quality films of Bi2Se3
• Clarifying ultrafast carrier dynamics in ultrathin films of the topological insulator Bi2Se3 using transient absorption spectroscopy
• Acoustic phonon dynamics in thin-films of the topological insulator Bi2Se3
• Two-dimensional electronic transport on the surface of 3D topological insulators
• Revealing Optical Transitions and Carrier Recombination Dynamics within the Bulk Band Structure of Bi2Se3
• Exciton diffusion in semiconducting single-wall carbon nanotubes studied by transient absorption microscopy
• Local photocurrent generation in thin films of the topological insulator Bi2Se3
• Photocurrents in Bi2Se3: bulk versus surface, and injection versus shift currents
• Femtosecond study of A1g phonons in the strong 3D topological insulators: From pump-probe to coherent control
• Effect of Mn doping on ultrafast carrier dynamics in thin films of the topological insulator Bi2Se3
• Observation of antiphase coherent phonons in the warped Dirac cone of Bi${}_2$Te${}_3$
• Role of matrix elements in the time-resolved photoemission signal
• Surface Optical and Bulk Acoustic Phonons in the Topological Insulator, Bi2Se2Te
• Current amplification and relaxation in Dirac systems
• Coherent surface-to-bulk vibrational coupling in the 2D topologically trivial insulator Bi2Se3 monitored by ultrafast transient absorption spectroscopy
• Investigation of structural and magneto-transport properties of PdTe2 single crystals
• Voigt effect-based wide-field magneto-optical microscope integrated in a pump-probe experimental setup
• Inverse Spin Hall Effect Induced by Asymmetric Illumination of Light on Topological Insulator Bi${}_2$Se${}_3$
• Comment on 'Unraveling Photoinduced Spin Dynamics in the Topological Insulator Bi2Se3'
• Two-photon IR pumped UV-Vis transient absorption spectroscopy of Dirac fermions in the 2D and 3D topological insulator Bi2Se3
• Nanosecond dynamics in intrinsic topological insulator ${\text{Bi}}_{2-x}{\text{Sb}}_x{\text{Se}}_3$ revealed by time-resolved optical reflectivity
• Diffusion of degenerate minority carriers in a p-type semiconductor
• Band structure of Bi surfaces formed on Bi2Se3 upon exposure to air
• Tracking the surface atomic motion in a coherent phonon oscillation
• Ultrafast Carrier Relaxation and Second Harmonic Generation in a Higher-Fold Weyl Fermionic System PtAl