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Experimental demonstration of Fermi surface effects at filling factor 5/2
R L Willett1, K W West, L N Pfeiffer
1Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey 07974, USA.
Physical Review Letters
|February 28, 2002
Summary
Researchers used surface acoustic waves (SAW) to detect Fermi surface properties in ultrahigh mobility heterostructures at the 5/2 filling factor. Enhanced conductivity suggests composite fermions may pair to form the 5/2 ground state.
Area of Science:
- Condensed matter physics
- Quantum Hall effect phenomena
Background:
- The 5/2 fractional quantum Hall state is a key area of research in condensed matter physics.
- Understanding its properties requires sensitive experimental probes.
Purpose of the Study:
- To investigate the Fermi surface properties of the 5/2 filling factor in ultrahigh mobility heterostructures.
- To explore the nature of the ground state at this filling factor using novel techniques.
Main Methods:
- Utilizing sub-0.5-micrometer surface acoustic waves (SAW) to probe heterostructures.
- Measuring conductivity changes at the 5/2 filling factor at elevated temperatures.
Main Results:
- Fermi surface properties were detected at the 5/2 filling factor at temperatures above the quantum Hall state formation.
- Enhanced conductivity was observed, indicating a quasiparticle mean-free path shorter than in the lowest Landau level.
Conclusions:
- Findings support the existence of a filled Fermi sea of composite fermions.
- Composite fermion pairing at lower temperatures is proposed as the mechanism for the 5/2 ground state.
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