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Interlayer Electron-Hole Friction in Tunable Twisted Bilayer Graphene Semimetal
D A Bandurin1, A Principi2, I Y Phinney3
1Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore.
Physical Review Letters
|December 3, 2022
Summary
Charge-neutral conducting systems in twisted bilayer graphene exhibit unique electron-hole interactions. Researchers observed strong friction between electrons and holes, revealing new conduction mechanisms in these materials.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Electronics
Background:
- Charge-neutral conducting systems possess unusual properties driven by electron-hole (e-h) interactions.
- Semimetallic phases can display unconventional responses to external fields, defying single-particle physics interpretations.
- Small-angle twisted bilayer graphene (SA TBG) is a tunable platform for studying these phenomena.
Purpose of the Study:
- To investigate interaction-limited electron conduction in charge-neutral SA TBG.
- To explore the transition between different transport regimes in these materials.
- To elucidate the conduction mechanisms in charge-neutral SA TBG.
Main Methods:
- Utilizing a dual-gated device architecture to control charge neutrality.
- Tuning the system from a Dirac fluid to a compensated two-component electron-hole Fermi liquid.
- Analyzing resistivity measurements, specifically the T^{2} dependence, to identify electron-hole friction.
Main Results:
- Demonstrated a smooth transition between different interaction-limited transport regimes in SA TBG.
- Observed strong mutual friction between spatially separated electrons and holes.
- Confirmed that the observed T^{2} resistivity aligns with developed electron-hole drag theory.
Conclusions:
- SA TBG provides a tunable system for studying electron-hole interactions in conducting materials.
- The observed friction and resistivity behavior clarify conduction mechanisms in charge-neutral SA TBG.
- This work offers a textbook example of transitions in interaction-limited transport regimes.
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