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${}_3$.

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Cited by in corpus (7)

• Time- and Angle-Resolved Photoemission Studies of Quantum Materials
• Coherent phonons in a $B{i}_{2}S{e}_3$ film generated by an intense single-cycle THz pulse
• Mode-selective coupling of coherent phonons to the Bi2212 electronic band structure
• Impact of ultrafast transport on the high-energy states of a photoexcited topological insulator
• Influence of local symmetry on lattice dynamics coupled to topological surface states
• Time-domain study of coupled collective excitations in quantum materials
• Analysis methodology of coherent oscillations in time- and angle-resolved photoemission spectroscopy