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Many-body effects on the rho(xx) ringlike structures in two-subband wells
Gerson J Ferreira1, Henrique J P Freire, J Carlos Egues
1Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos, São Paulo, Brazil.
Physical Review Letters
|April 7, 2010
Summary
Ringlike structures in two-dimensional electron gases break at low temperatures due to a quantum Hall ferromagnetic phase transition, showing high spin polarization. Increasing magnetic field tilt angles also cause ring collapse.
Area of Science:
- Condensed matter physics
- Quantum phenomena in electron systems
Background:
- Two-dimensional electron gases (2DEGs) in quantum wells exhibit complex behavior under magnetic fields.
- Longitudinal resistivity shows ringlike structures in density-magnetic-field diagrams due to Landau level crossings.
Purpose of the Study:
- Investigate the shape and spin polarization of resistivity rings in 2DEGs.
- Analyze the influence of temperature and magnetic field tilt on these structures.
- Explore the underlying physics, including quantum Hall ferromagnetic phase transitions.
Main Methods:
- Spin density functional theory (SDFT) calculations.
- Linear response theory.
- Analysis of resistivity in density-magnetic-field diagrams.
Main Results:
- Resistivity rings exhibit "breaking" at low temperatures, indicating a quantum Hall ferromagnetic phase transition with ~50% spin polarization.
- Increasing magnetic field tilt angles lead to ring collapse at a critical angle due to inter-Landau level coupling and exchange-correlation effects.
Conclusions:
- The study explains the observed ring structures and their evolution with temperature and magnetic field tilt.
- Findings are consistent with experimental data, particularly regarding spin polarization and ring collapse phenomena.
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