Current-induced excitonic condensation in bilayer systems

A. Osterkorn,1 D. Golež1,2

1Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia

2Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 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 technologically highly relevant features like superfluid energy transport. 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 static Hartree-Fock and second order Born approximations. We compare results from dynamical mean-field theory to simulations in one spatial dimension to shed light on the strong impact of dimensionality on the formation of the excitonic state. To go beyond the quasi-stationary case, we discuss results of time-dependent simulations of a driven four-band model in one spatial dimension, which is coupled to a bosonic bath.

1. Ma, L. et al. Nature 598, 585–589 (2021)
2. Ming Xie and A.H. MacDonald, PRL 121, 067702 (2018)