Berlin 2024 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 69: Nonequilibrium Quantum Systems II (joint session TT/DY)

TT 69.12: Vortrag

Donnerstag, 21. März 2024, 12:30–12:45, H 3025

Current-induced excitonic condensation in bilayer systems — •Alexander Osterkorn and Denis Golež — Institut "Jožef Stefan", Jamova cesta 39, 1000 Ljubljana, Slovenia

Excitons are correlated electron-hole pairs in multi-band electron systems, which can condense and form ordered phases of matter called excitonic insulators. These are expected to display novel and interesting features like superfluid energy transport and perfect Coulomb drag. While it is experimentally challenging to identify real materials hosting equilibrium excitonic order, out-of-equilibrium protocols open up an independent route to stabilize excitonic condensates. Ma et.al. [1] proposed a gated semiconductor bilayer architecture, in which an applied voltage bias allows for the continuous creation of interlayer excitons by means of an induced electrical current. We model the setup starting from the quasi-stationary situation [2] within the Hartree-Fock and second order Born approximations and discuss the strong impact of dimensionality on the formation of the excitonic state. In order to go beyond the static picture, we demonstrate the dynamical formation of a steady-state subsequent to a switch-on of the voltage bias within real-time DMFT. We discuss how the formation of an excitonic condensate depends on steady-state temperature and doped carrier concentration.

[1] L. Ma et al., Nature 598 (2021) 585

[2] M. Xie, A.H. MacDonald, Phys. Rev. Lett. 121 (2018) 067702

Keywords: exciton; DMFT; bilayer; condensation; excitonic insulator