Abstract
We perform time- and angle-resolved photoemission spectroscopy of a prototypical topological insulator (TI) 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.
- Received 11 April 2012
DOI:https://doi.org/10.1103/PhysRevLett.109.127401
© 2012 American Physical Society
Synopsis
Electrons that Take the Heat
Published 20 September 2012
An ultra-high-speed camera has captured the cooling of surface electrons in topological insulators.
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