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

We report on observation of the infrared photoresistance of twisted bilayer graphene (tBLG) 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 tBLG. 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 tBLG.

Automated summary

In this study, the infrared photoresistance of twisted bilayer graphene (tBLG) under continuous quantum cascade laser illumination at a frequency of 57.1 THz was observed. The photoresistance exhibited a complex sign-alternating behavior under variations of temperature and back gate voltage, and showed giant resonance-like enhancements at certain gate voltages. The structure of the photoresponse correlated with weaker features in the dark dc resistance, indicating the complex band structure of tBLG. The observed photoresistance was well explained by a bolometric model, suggesting ultrafast thermalization of the photoexcited electron-hole pairs across different temperatures and gate voltages. This study establishes photoresistance as a highly sensitive probe for temperature variations in electronic transport of tBLG.