Ultrafast surface carrier dynamics in the topological insulator Bi2Te3

Abstract

We discuss the ultrafast evolution of the surface electronic structure of the topological insulator Bi${}_2$Te${}_3$ following a femtosecond laser excitation. Using time and angle resolved photoelectron spectroscopy, we provide a direct real-time visualisation of the transient carrier population of both the surface states and the bulk conduction band. We find that the thermalization of the surface states is initially determined by interband scattering from the bulk conduction band, lasting for about 0.5 ps; subsequently, few ps are necessary for the Dirac cone non-equilibrium electrons to recover a Fermi-Dirac distribution, while their relaxation extends over more than 10 ps. The surface sensitivity of our measurements makes it possible to estimate the range of the bulk-surface interband scattering channel, indicating that the process is effective over a distance of 5 nm or less. This establishes a correlation between the nanoscale thickness of the bulk charge reservoir and the evolution of the ultrafast carrier dynamics in the surface Dirac cone.

References in corpus (5)

• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Topological Field Theory of Time-Reversal Invariant Insulators
• Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3
• Ultrafast carrier and phonon dynamics in Bi2Se3 crystals

Cited by in corpus (2)

• Ultrafast photodoping and effective Fermi-Dirac distribution of the Dirac particles in Bi2Se3
• Unoccupied Topological States on Bismuth Chalcogenides