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Imaging transport resonances in the quantum Hall effect.
G A Steele1, R C Ashoori, L N Pfeiffer
1Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Physical Review Letters
|October 4, 2005
Summary
Scanning capacitance probe microscopy reveals quantum dot islands in quantum Hall systems. These islands enable resonant tunneling, significantly boosting conductance across incompressible strips.
Area of Science:
- Condensed Matter Physics
- Quantum Phenomena
Background:
- The quantum Hall system exhibits unique electronic properties due to strong magnetic fields.
- Understanding transport mechanisms in two-dimensional electron systems (2DES) is crucial for quantum device development.
Purpose of the Study:
- To investigate transport phenomena in the quantum Hall system using scanning capacitance probe microscopy.
- To elucidate the role of disorder in creating novel transport pathways.
Main Methods:
- Utilized a scanning capacitance probe to image charge transport.
- Applied a DC bias voltage to the probe tip to induce and manipulate incompressible strips (IS) in the 2DES.
- Analyzed the impact of short-range disorder on IS formation and transport characteristics.
Main Results:
- Demonstrated that a scanning probe can induce mobile, ring-shaped incompressible strips in the 2DES.
- Observed the formation of quantum dot islands within the IS due to local disorder.
- Measured a significant enhancement (over 4 orders of magnitude) in conductance attributed to resonant tunneling through these islands.
Conclusions:
- Resonant tunneling through disorder-induced quantum dot islands is a primary transport mechanism across incompressible strips.
- Scanning capacitance probe microscopy offers a quantitative method to assess disorder in 2DES.
- This work provides insights into controlling and understanding transport in quantum Hall systems.