Self-energy dynamics and mode-specific phonon threshold effect in a Kekulé-ordered graphene

Abstract

Electron-phonon interaction and related self-energy are fundamental to both the equilibrium properties and non-equilibrium relaxation dynamics of solids. Although electron-phonon interaction has been suggested by various time-resolved measurements to be important for the relaxation dynamics of graphene, the lack of energy- and momentum-resolved self-energy dynamics prohibits direct identification of the role of specific phonon modes in the relaxation dynamics. Here by performing time- and angle-resolved photoemission spectroscopy measurements on a Kekulé-ordered graphene with folded Dirac cones at the $\Gamma$ point, we have succeeded in resolving the self-energy effect induced by coupling of electrons to two phonons at ${\Omega }_1$ = 177 meV and ${\Omega }_2$ = 54 meV and revealing its dynamical change in the time domain. Moreover, these strongly coupled phonons define energy thresholds, which separate the hierarchical relaxation dynamics from ultrafast, fast to slow, thereby providing direct experimental evidence for the dominant role of mode-specific phonons in the relaxation dynamics

Kekulé-ordered graphene 2: Self-energy dynamics and phonon threshold effect revealed by time- and angle-resolved photoemission spectroscopy

References in corpus (8)

• The electronic properties of graphene
• Experimental evidence of chiral symmetry breaking in Kekulé-ordered graphene
• Anisotropic Electron-Phonon Coupling and Dynamical Nesting on the Graphene Sheets in CaC6
• Kohn anomaly and interplay of electron-electron and electron-phonon interactions in epitaxial graphene
• Enhanced electron-phonon coupling in graphene with periodically distorted lattice
• Ultrafast quenching of electron-boson interaction and superconducting gap in a cuprate superconductor
• Phonon-pump XUV-photoemission-probe in graphene: evidence for non-adiabatic heating of Dirac carriers by lattice deformation
• Ultrafast dynamics of electron-phonon coupling in a metal

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• Ultrafast dynamics of electrons and phonons: from the two-temperature model to the time-dependent Boltzmann equation
• Coexistence of extended flat band and Kekulé order in Li-intercalated graphene
• Ultrafast time- and angle-resolved photoemission spectroscopy with widely tunable probe photon energy of 5.3-7.0 eV for investigating dynamics of three-dimensional materials
• Observation of Floquet-induced gap in graphene
• High harmonic generation light source with polarization selectivity and sub-100-$\mu$m beam size for time- and angle-resolved photoemission spectroscopy
• Hidden charge density wave induced shadow bands and ultrafast dynamics of CuTe investigated using time-resolved ARPES
• Kekulé valence bond order in the honeycomb lattice optical Su-Schrieffer-Heeger Model and its relevance to Graphene
• Temperature and magnetic field dependent $g$-factors in electron spin resonance spectroscopy