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Unconventional Correlation between Quantum Hall Transport Quantization and Bulk State Filling in Gated Graphene
Yong-Tao Cui1, Bo Wen2, Eric Y Ma1
1Geballe Laboratory for Advanced Materials (GLAM), Stanford University, Stanford, California 94305, USA.
Physical Review Letters
|November 12, 2016
Summary
Quantized transport in graphene
Area of Science:
- Condensed matter physics
- Materials science
Background:
- The quantum Hall effect (QHE) in two-dimensional electron systems (2DES) is a hallmark of topological physics.
- Understanding the precise conditions for quantized transport is crucial for fundamental science and potential applications.
Purpose of the Study:
- To investigate the relationship between quantized transport and the filling of bulk Landau levels in gated graphene devices.
- To clarify the mechanism of transport quantization under carrier accumulation via gating.
Main Methods:
- Simultaneous measurements of transport properties and scanning microwave impedance microscopy (sMIM).
- Utilizing gated graphene devices to control carrier density and Landau level filling.
Main Results:
- Quantized transport was observed to occur *before* the complete filling of bulk Landau levels.
- The bulk of the graphene device remained conductive when quantized transport initiated, contrary to expectations.
- This indicates a revised understanding of transport quantization in gated systems.
Conclusions:
- The findings challenge conventional models of transport quantization in the quantum Hall regime.
- This work has significant implications for studying the quantum Hall effect in graphene and other 2D materials.
- It provides new insights into topological states in 2DES.
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