Infrared photoresistance as a sensitive probe of electronic transport in twisted bilayer graphene

TL;DR

This study demonstrates that infrared photoresistance measurements can sensitively probe electronic transport properties in twisted bilayer graphene, revealing complex behaviors linked to its band structure and ultrafast thermalization processes.

Contribution

It introduces infrared photoresistance as a novel, highly sensitive method for investigating electronic transport in twisted bilayer graphene, supported by a bolometric model.

Findings

Photoresistance exhibits sign-alternating behavior with temperature and gate voltage.

Giant resonance-like enhancements occur at specific gate voltages.

Photoresponse correlates with features in dark dc resistance.

Abstract

We report on observation of the infrared photoresistance of twisted bilayer graphene under continuous quantum cascade laser illumination at a frequency of 57.1 THz. The photoresistance shows an intricate sign-alternating behavior under variations of temperature and back gate voltage, and exhibits giant resonance-like enhancements at certain gate voltages. The structure of the photoresponse correlates with weaker features in the dark dc resistance reflecting the complex band structure of twisted bilayer graphene. It is shown that the observed photoresistance is well captured by a bolometric model describing the electron and hole gas heating, which implies an ultrafast thermalization of the photoexcited electron-hole pairs in the whole range of studied temperatures and back gate voltages. We establish that photoresistance can serve a highly sensitive probe of the temperature variations of electronic transport in twisted bilayer graphene.