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Competing Fractional Quantum Hall and Electron Solid Phases in Graphene.
Shaowen Chen1,2, Rebeca Ribeiro-Palau1,3, Kang Yang4,5
1Department of Physics, Columbia University, New York, 10027 New York, USA.
Physical Review Letters
|February 6, 2019
Summary
We observed the reentrant integer quantum Hall effect in graphene, driven by competing quantum Hall states and electron solids. Graphene
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Hall Effect Studies
Background:
- The integer quantum Hall effect (IQHE) is a hallmark of 2D electron systems in strong magnetic fields.
- Reentrant IQHE has been observed in GaAs/AlGaAs heterostructures, attributed to competing quantum Hall states and electron solids.
- Graphene's unique electronic properties offer a tunable platform for exploring quantum phenomena.
Purpose of the Study:
- To experimentally observe and characterize the reentrant integer quantum Hall effect in graphene.
- To investigate the role of competing incompressible fractional quantum Hall states and electron solid phases.
- To measure the temperature-magnetic field (B-T) phase diagram of the electron solid phase in graphene.
Main Methods:
- Experimental measurements of quantum Hall effect in graphene.
- Tuning of electron density and magnetic field to probe phase transitions.
- Analysis of the B-T phase diagram to identify electron liquid-solid transitions.
Main Results:
- Experimental observation of reentrant integer quantum Hall effect in graphene at the N=2 Landau level.
- Identification of a competition between fractional quantum Hall states and electron solid phases.
- Measurement of the B-T phase diagram, showing melting temperature scaling with magnetic field.
Conclusions:
- Graphene exhibits reentrant integer quantum Hall effect analogous to GaAs/AlGaAs systems.
- Spin and valley degrees of freedom are suggested to influence ground state energy and reentrant states.
- A comprehensive phase diagram of the electron liquid-solid transition in graphene was constructed.
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