Year: 2012
Type: article
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 visualization 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 picoseconds are necessary for the Dirac cone nonequilibrium 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.
Source: Nano Letters
DOI: 10.1021/nl301035x
Institutions: Université Paris-Sud, Centre National de la Recherche Scientifique, École Polytechnique, École Nationale Supérieure de Techniques Avancées, Laboratoire d'Optique Appliquée, Georgia Institute of Technology, Purdue University West Lafayette, Synchrotron SOLEIL, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Laboratoire des Solides Irradiés
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2064297692