Observation of antiphase coherent phonons in the warped Dirac cone of Bi${}_2$Te${}_3$

Abstract

In this Rapid Communication we investigate the coupling between excited electrons and phonons in the highly anisotropic electronic structure of the prototypical topological insulator Bi${}_2$Te${}_3$. Using time- and angle-resolved photoemission spectroscopy we are able to identify the emergence and ultrafast temporal evolution of the longitudinal-optical A${}_{1g}$ coherent-phonon mode in Bi${}_2$Te${}_3$. We observe an antiphase behavior in the onset of the coherent-phonon oscillations between the $\overline{\Gamma K}$ and the $\overline{\Gamma M}$ high-symmetry directions that is consistent with warping. The qualitative agreement between our density-functional theory calculations and the experimental results reveals the critical role of the anisotropic coupling between Dirac fermions and phonon modes in the topological insulator Bi${}_2$Te${}_3$.

References in corpus (8)

• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• First direct observation of Spin-textures in Topological Insulators : Spin-resolved ARPES as a probe of topological quantum spin Hall effect and Berry's phase
• Ultrafast surface carrier dynamics in the topological insulator Bi2Te3
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• Spatially resolved femtosecond pump-probe study of topological insulator Bi2Se3
• Bulk Band Structure of Bi${}_2$Te${}_3$
• Anisotropic effect of warping on the lifetime broadening of topological surface states in angle-resolved photoemission from Bi${}_2$Te${}_3$
• Polarization dependence of coherent phonon generation and detection in the 3D topological insulator Bi2Te3

Cited by in corpus (1)

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