학술논문
Measurement of Intrinsic Dirac Fermion Cooling on the Surface of the Topological Insulator Bi2 Se3 Using Time-Resolved and Angle-Resolved Photoemission Spectroscopy.
Document Type
Article
Author
Source
Subject
*FERMIONS
*COOLING
*SELENIDES
*SURFACES (Technology)
*DIRAC equation
*ELECTRIC insulators & insulation
*TIME-resolved spectroscopy
*PHOTOELECTRON spectroscopy
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Language
ISSN
0031-9007
Abstract
We perform time- and angle-resolved photoemission spectroscopy of a prototypical topological insulator (TI) Bi2Se3 to study the ultrafast dynamics of surface and bulk electrons after photoexcitation. By analyzing the evolution of surface states and bulk band spectra, we obtain their electronic temperature and chemical potential relaxation dynamics separately. These dynamics reveal strong phonon-assisted surface-bulk coupling at high lattice temperature and total suppression of inelastic scattering between the surface and the bulk at low lattice temperature. In this low temperature regime, the unique cooling of Dirac fermions in TI by acoustic phonons is manifested through a power law dependence of the surface temperature decay rate on carrier density. [ABSTRACT FROM AUTHOR]