Comparing the generalized Kadanoff-Baym ansatz with the full Kadanoff-Baym equations for an excitonic insulator out of equilibrium
Tuovinen R, Golez D, Eckstein M, Sentef MA (2020)
Publication Type: Journal article
Publication year: 2020
Journal
Book Volume: 102
Journal Issue: 11
DOI: 10.1103/PhysRevB.102.115157
Abstract
We investigate out-of-equilibrium dynamics in an excitonic insulator (EI) with a finite-momentum pairing perturbed by a laser-pulse excitation and a sudden coupling to fermionic baths. The transient dynamics of the excitonic order parameter is resolved using the full nonequilibrium Green's function approach and the generalized Kadanoff-Baym ansatz (GKBA) within the second-order Born approximation. The comparison between the two approaches after a laser-pulse excitation shows a good agreement in the weak and the intermediate photodoping regime. In contrast, the laser-pulse dynamics resolved by the GKBA does not show a complete melting of the excitonic order after a strong excitation. Instead we observe persistent oscillations of the excitonic order parameter with a predominant frequency given by the renormalized equilibrium band gap. This anomalous behavior can be overcome within the GKBA formalism by coupling to an external bath, which leads to a transition of the EI system toward the normal state. We analyze the long-time evolution of the system and distinguish decay timescales related to dephasing and thermalization.
Authors with CRIS profile
Involved external institutions
University of Turku / Turun yliopisto
Finland (FI)
Simons Foundation
United States (USA) (US)
Max-Planck-Instituts für Struktur und Dynamik der Materie (MPSD) / Max Planck Institute for the Structure and Dynamics of Matter
Germany (DE)
Finland (FI)
Simons Foundation
United States (USA) (US)
Max-Planck-Instituts für Struktur und Dynamik der Materie (MPSD) / Max Planck Institute for the Structure and Dynamics of Matter
Germany (DE)
How to cite
APA:
Tuovinen, R., Golez, D., Eckstein, M., & Sentef, M.A. (2020). Comparing the generalized Kadanoff-Baym ansatz with the full Kadanoff-Baym equations for an excitonic insulator out of equilibrium. Physical Review B, 102(11). https://doi.org/10.1103/PhysRevB.102.115157
MLA:
Tuovinen, Riku, et al. "Comparing the generalized Kadanoff-Baym ansatz with the full Kadanoff-Baym equations for an excitonic insulator out of equilibrium." Physical Review B 102.11 (2020).
BibTeX: Download