Electrically controlled two-dimensional electron-hole fluids

Recent advances in experimental techniques have opened up the possibility of electrical control of electron-hole bilayer systems. In this talk I will discuss the electronic properties of a dual-gated electron-hole bilayer in which the two layers are separated by a perfectly opaque tunnel barrier. Combining an electrostatic and thermodynamic analysis [1] with mean-field theory estimates of interacting system chemical potentials, we explain the dependence of the electron and hole densities on the two gate voltages. We find a finite area in gate voltage parameter space over which electron and hole densities are equal and the electron-hole pair density depends only on the bias voltage which acts like a chemical potential for excitons. I will briefly discuss the transport properties of exciton circuits formed in systems with two or more exciton reservoirs, and a recent related experimental study [2] of electrically controlled bilayers that realizes a non-equilibrium steady-state instead of a quasi-equilibrium.

[1] Y. Zeng and A. H. MacDonald. Phys. Rev. B 102, 085154 (2020).
[2] Z. Wang, et al. Nature 574, 7776 (2019).