Geometric Stiffness in Interlayer Exciton Condensates

TL;DR

This paper reveals how quantum geometry influences the phase stiffness of interlayer exciton condensates in TMD bilayers, showing a geometric contribution that enhances condensate robustness and raises the BKT transition temperature.

Contribution

It identifies and quantifies the geometric contribution to phase stiffness in interlayer exciton condensates, a novel insight into their formation and stability.

Findings

Quantum geometry significantly enhances phase stiffness.

Geometric contribution increases BKT temperature.

Realistic estimates suggest feasible experimental realization.

Abstract

Recent experiments have confirmed the presence of interlayer excitons in the ground state of transition metal dichalcogenide (TMD) bilayers. The interlayer excitons are expected to show remarkable transport properties when they undergo Bose condensation. In this work, we demonstrate that quantum geometry of Bloch wavefunctions plays an important role in the phase stiffness of the Interlayer Exciton Condensate (IEC). Notably, we identify a geometric contribution that amplifies the stiffness, leading to the formation of a robust condensate with an increased BKT temperature. Our results have direct implications for the ongoing experimental efforts on interlayer excitons in materials that have non-trivial quantum geometry. We provide quantitative estimates for the geometric contribution in TMD bilayers through a realistic continuum model with gated Coulomb interaction, and find that the substantially increased stiffness allows for an IEC to be realized at amenable experimental conditions.