Resistive signature of excitonic coupling in an electron-hole double layer with a middle barrier

TL;DR

This study reveals a resistive signature of excitonic coupling in a double-layer electron-hole system, showing enhanced scattering near charge neutrality that cannot be explained by Fermi-liquid theory, highlighting Coulomb interaction effects.

Contribution

It demonstrates the experimental observation of excitonic coupling effects through resistive signatures in a carefully designed double-layer device with negligible tunneling.

Findings

Enhanced resistive scattering near charge neutrality

Evidence of excitonic coupling from transport measurements

Coulomb interactions dominate despite disorder

Abstract

We study the interlayer scattering mediated by long-range Coulomb interaction between electrons (density n) and holes (p) in a double-layer system. The gated device is made of InAs (e) and InGaSb (h) quantum wells separated by a AlSb middle barrier such that the interlayer tunneling is negligibly small. By using independent-layer contacts we measure the transport tensor \r{ho}_xx and \r{ho}_xy that are solely from the InAs layer, while sweeping p in the InGaSb layer. We found a strongly enhanced resistive scattering signal as the carrier densities approach a total charge neutrality, n = p, which cannot be described by the Fermi-liquid theory. Results of data analysis for density, temperature, and magnetic field dependences are consistent with the emergence of excitonic coupling between the two layers, stressing the dominance of Coulomb interaction even in the presence of disorder.