SKM 2021 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 3: Poster Session I

HL 3.22: Poster

Montag, 27. September 2021, 10:00–13:00, P

Excitation-induced quenching and optical amplification in a CDW-phase of a two dimensional material — •Stephan Michael and Hans Christian Schneider — Department of Physics and Research Center OPTIMAS, TU Kaiserslautern, P.O. Box 3049, 67653 Kaiserslautern, Germany

The optical excitation of two dimensional materials like transition metal dichalcogenides (TMDs) in connection with their rich electronic phase diagrams offer new ways to manipulate material properties on ultrafast timescales [1,2]. We study theoretically the appearance and the quenching of a CDW phase in a model system of a two dimensional material due to optical excitation with time-dependent interaction matrix elements and screening effects. We describe the excitonic and coherent-phonon effects in the band-dynamics by electron-hole and electron-phonon coupling. The non-equilibrium carrier dynamics includes the optical excitation, the carrier-carrier scattering as well as the carrier-phonon scattering. We discuss how interaction processes affect anomalous expectation values and use projection techniques to illustrate the time-dependent appearance of additional bands. We propose an optical amplification effect in the mid-infrared up to infrared regime with a potential for high-frequency modulation.

[1] S. Mathias et. al., Nat. Commun. 7, 12902 (2016).

[2] S. Michael and H. C. Schneider, Phys. Rev. B 100, 035431 (2019).