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arXiv · 2307.07348

Mott-Enhanced Exciton Condensation in a Hubbard bilayer

Samuele Giuli·Adriano Amaricci·Massimo Capone
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Abstract

We study the conditions to realize an excitonic condensed phase in an electron-hole bilayer system with local Hubbard-like interactions at half-filling, where we can address the interplay with Mott localization. Using Dynamical Mean-Field Theory, we find that an excitonic state is stable in a sizeable region of a phase diagram spanned by the intra-layer (U) and inter-layer (V) interactions. The latter term is expected to favour the excitonic phase which is indeed found in a slice of the phase diagram with V > U . Remarkably, we find that when U is large enough, the excitonic region extends also for U > V in contrast with naive expectations. The extended stability of the excitonic phase can be linked to in-layer Mott localization and inter-layer spin correlations. Using a mapping to a model with attractive inter-layer coupling, we fully characterize the condensate phase in terms of its superconducting counterpart, thereby addressing its coherence and correlation length.

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Samuele Giuli, Adriano Amaricci, Massimo Capone. 2023-07-14. Mott-Enhanced Exciton Condensation in a Hubbard bilayer. https://doi.org/10.1103/physrevb.108.165150

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