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Tilt-induced anisotropic to isotropic phase transition at ν = 5/2
Jing Xia1, Vaclav Cvicek, J P Eisenstein
1California Institute of Technology, Pasadena, 91125, USA.
Physical Review Letters
|January 15, 2011
Summary
A modest in-plane magnetic field destroys fractional quantum Hall states. These states are replaced by compressible phases, with transitions driven by Landau level mixing and confinement potential width.
Area of Science:
- Condensed Matter Physics
- Quantum Hall Effect
Background:
- Fractional quantized Hall states (FQHS) are exotic states of matter observed in 2D electron systems.
- The FQHS at filling factors \(ν = 5/2\) and \(ν = 7/2\) are particularly intriguing due to their potential for non-Abelian statistics.
Purpose of the Study:
- To investigate the effect of in-plane magnetic fields on FQHS at \(ν = 5/2\) and \(ν = 7/2\).
- To understand the nature of the emergent compressible phases and the transitions between them.
- To explore the influence of Landau level mixing and confinement potential width on energy gaps.
Main Methods:
- Experimental measurements of quantum Hall states under varying in-plane magnetic fields.
- Analysis of phase transitions and electronic properties.
Main Results:
- A modest in-plane magnetic field destroys FQHS at \(ν = 5/2\) and \(7/2\), leading to anisotropic compressible phases.
- At larger in-plane fields, these phases transition to isotropic compressible phases, resembling the composite fermion fluid at \(ν = 1/2\).
- Evidence suggests Landau level mixing from different electric subbands drives this transition.
- Observed surprising dependencies of energy gaps at \(ν = 5/2\) and \(7/3\) on confinement potential width.
Conclusions:
- In-plane magnetic fields significantly alter the electronic phases in 2D systems.
- Landau level mixing plays a crucial role in the observed phase transitions.
- Confinement potential engineering offers a way to tune the properties of quantum Hall states.
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