Quadriexcitons and excitonic condensate in a symmetric electron-hole bilayer with valley degeneracy

Abstract

Using quantum Monte Carlo simulations we have mapped out the zero temperature phase diagram of a symmetric electron-hole bilayer with twofold valley degeneracy, as function of the interlayer distance $d$ and in-layer density $n$. We find that the effect of the valley degeneracy is to shrink the region of stability of the excitonic condensate, in favor of quadriexcitons at small $d$ and of the four-component plasma at large $d$, with minor effects on the value of the excitonic condensate fraction. The enclosure of the condensate in a density window possibly explains why anomalous tunnelling conductivity, interpreted as signature of condensation, is observed only between two finite values of carrier density in graphene bilayers. Our phase diagram may provide directions to select device parameters for future experiments.

arXiv commentpaper: 5 pages and 4 figures; supplemental info: 5 pages, 7 figures, 2 tables

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Cited by in corpus (6)

• Polaron spectroscopy of a bilayer excitonic insulator
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• Next-generation EDIpack: A Lanczos-based package for quantum impurity models featuring general broken-symmetry phases, flexible bath topologies and multi-platform interoperability
• Energetic comparison of exciton gas versus electron-hole plasma in a bilayer two-dimensional electron-hole system
• Quadriexciton binding energy in electron-hole bilayers
• Beyond Random Phase Approximation in electron-hole bilayer superfluidity