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Strongly coupled edge states in a graphene quantum Hall interferometer.
Thomas Werkmeister1, James R Ehrets2, Yuval Ronen2,3
1John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
Nature Communications
|August 2, 2024
Summary
Quantum Hall effect interferometers reveal how electron interactions cause apparent particle pairing. Tuning electron density in graphene clarifies the link between phase jumps and Aharonov-Bohm frequency doubling in edge channels.
Area of Science:
- Condensed Matter Physics
- Quantum Mechanics
- Materials Science
Background:
- Quantum Hall effect (QHE) edge channels enable studies of fundamental physics.
- Fabry-Pérot (FP) interferometers in QHE systems reveal quasiparticle statistics and anomalous phenomena.
- Aharonov-Bohm (AB) interference frequency doubling suggests electron pairing into exotic quasiparticles.
Purpose of the Study:
- To investigate the connection between interference phase jumps and AB frequency doubling in QHE FP interferometers.
- To elucidate the role of electron-electron interactions in observed pairing phenomena.
- To utilize a tunable graphene-based QHE FP interferometer for in-situ interaction studies.
Main Methods:
- Fabrication and operation of a tunable graphene-based quantum Hall effect Fabry-Pérot interferometer.
- In-situ tuning of electron density across various filling factors ( to ).
- Measurement and analysis of interference phase jumps and Aharonov-Bohm oscillations.
Main Results:
- Observed periodic interference phase jumps correlating with Aharonov-Bohm frequency doubling.
- Demonstrated that repulsive interactions between spin-split edge channels drive the apparent pairing.
- Showcased the effect of charge screening between localized and extended edge channels.
Conclusions:
- Repulsive interactions and charge quantization in edge channels explain AB frequency doubling.
- Graphene QHE interferometers are sensitive probes of microscopic interactions in one-dimensional systems.
- Enables future research on correlated electrons in 1D channels using tunable graphene devices.
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