Time-dependent many-body treatment of electron-boson dynamics: Application to plasmon-accompanied photoemission

Schüler, Michael; Berakdar, Jamal; Pavlyukh, Y.

doi:10.1103/physrevb.93.054303

Cited by 48 publications

(55 citation statements)

References 95 publications

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“…However, because of a dynamical sign problem [33] it is difficult to access the time scales needed to study the relatively slow dynamics of phonons and order parameters. In order to avoid this difficulty, we employ the self-consistent (renormalized) Migdal approximation [34][35][36][37][38][39][40][41][42], which is justified when the phonon frequency ω 0 is small compared to the electronic bandwidth [34][35][36]38,40]. In the self-consistent Migdal approximation, the electron self-energy (ˆ ) and phonon self-energy ( ) in the effective impurity model are given bŷ…”

Section: Model and Methodsmentioning

confidence: 99%

Multiple amplitude modes in strongly coupled phonon-mediated superconductors

et al. 2016

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We study collective amplitude modes of the superconducting order parameter in strongly coupled electronphonon systems described by the Holstein model using the nonequilibrium dynamical mean-field theory with the self-consistent Migdal approximation as an impurity solver. The frequency of the Higgs amplitude mode is found to coincide with the superconducting gap even in the strongly coupled (beyond BCS) regime. Besides the Higgs mode, we find another collective mode involving the dynamics of both the phonons and the superconducting order parameter. The frequency of this mode, higher than twice the renormalized phonon frequency in the superconducting phase, is shown to reflect a strong electron-mediated phonon-phonon interaction. Both of collective modes are predicted to contribute to time-resolved photoemission spectra after a strong laser pump as vertex corrections to produce resonance peaks, which allows one to distinguish them from quasiparticle excitations.

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Section: Model and Methodsmentioning

confidence: 99%

Multiple amplitude modes in strongly coupled phonon-mediated superconductors

et al. 2016

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“…[61][62][63] A similar quantity is used in the context of quantum transport where the electrons of a molecular junction can move in and out of the junction by tunneling from and to the leads. [64][65][66] The complex absorbing potential in quantum mechanics can be seen as a time-local approximation to Σ emb .…”

Section: Nonequilibrium Photocurrentmentioning

confidence: 99%

First-principles approach to excitons in time-resolved and angle-resolved photoemission spectra

et al. 2016

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We show that any quasi-particle or GW approximation to the self-energy does not capture excitonic features in time-resolved (TR) photoemission spectroscopy. In this work we put forward a first-principles approach and propose a feasible diagrammatic approximation to solve this problem. We also derive an alternative formula for the TR photocurrent which involves a single time-integral of the lesser Green's function. The diagrammatic approximation applies to the relaxed regime characterized by the presence of quasi-stationary excitons and vanishing polarization. The main distinctive feature of the theory is that the diagrams must be evaluated using excited Green's functions. As this is not standard the analytic derivation is presented in detail. The final result is an expression for the lesser Green's function in terms of quantities that can all be calculated ab initio. The validity of the proposed theory is illustrated in a one-dimensional model system with a direct gap. We discuss possible scenarios and highlight some universal features of the exciton peaks. Our results indicate that the exciton dispersion can be observed in TR and angle-resolved photoemission.

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“…where T γ is the contour-time ordering operator and · is an ensemble average [47,48,52]. The equations of motion for the Green's function can be expressed through the time evolution of the field operatorsφ, and they read as (matrices in the 2N × 2N representation are from now on denoted with boldface…”

Section: A Transport Setup and Assumptionsmentioning

confidence: 99%

Phononic heat transport in the transient regime: An analytic solution

et al. 2016

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We investigate the time-resolved quantum transport properties of phonons in arbitrary harmonic systems connected to phonon baths at different temperatures. We obtain a closed analytic expression of the time-dependent one-particle reduced density matrix by explicitly solving the equations of motion for the nonequilibrium Green's function. This is achieved through a well-controlled approximation of the frequency-dependent bath self-energy. Our result allows for exploring transient oscillations and relaxation times of local heat currents, and correctly reduces to an earlier known result in the steady-state limit. We apply the formalism to atomic chains, and benchmark the validity of the approximation against full numerical solutions of the bosonic Kadanoff-Baym equations for the Green's function. We find good agreement between the analytic and numerical solutions for weak contacts and baths with a wide energy dispersion. We further analyze relaxation times from low to high temperature gradients.

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Time-dependent many-body treatment of electron-boson dynamics: Application to plasmon-accompanied photoemission

Cited by 48 publications

References 95 publications

Multiple amplitude modes in strongly coupled phonon-mediated superconductors

Multiple amplitude modes in strongly coupled phonon-mediated superconductors

First-principles approach to excitons in time-resolved and angle-resolved photoemission spectra

Phononic heat transport in the transient regime: An analytic solution

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