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Oscillating Nernst-Ettingshausen effect in bismuth across the quantum limit
Kamran Behnia1, Marie-Aude Méasson, Yakov Kopelevich
1Laboratoire de Physique Quantique (CNRS), ESPCI, 10 Rue de Vauquelin, 75231 Paris, France.
Physical Review Letters
|May 16, 2007
Summary
Researchers studied metallic thermoelectricity in bismuth under magnetic fields. They observed unique, large oscillating thermoelectric responses, particularly when electrons reached the lowest Landau level, with implications for future theories.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Phenomena
Background:
- Elemental bismuth exhibits a unique electronic structure with a low carrier density.
- Moderate magnetic fields can quantize electron energy levels into Landau levels.
- Confining electrons to the lowest Landau level is crucial for exploring exotic quantum effects.
Purpose of the Study:
- To investigate metallic thermoelectricity in elemental bismuth under conditions where electrons are confined to the lowest Landau level.
- To characterize the thermoelectric response, specifically the Nernst and Ettingshausen effects, in this quantum regime.
- To compare experimental observations with theoretical predictions, particularly those involving edge states.
Main Methods:
- Experimental measurement of thermoelectric coefficients in elemental bismuth subjected to a magnetic field.
- Focus on the regime where electrons occupy the lowest Landau level.
- Analysis of the off-diagonal thermoelectric response, including oscillating components.
Main Results:
- Observed a significant off-diagonal thermoelectric response, with oscillating components exceeding the background.
- Identified sharp peaks in both Nernst and Ettingshausen coefficients when the first Landau level aligns with the Fermi energy.
- Noted a temperature-independent maximum in the Ettingshausen coefficient under specific conditions.
Conclusions:
- The study presents the first investigation of metallic thermoelectricity in the lowest Landau level regime in bismuth.
- Observed thermoelectric phenomena that are not yet fully understood, suggesting new physics.
- Qualitative agreement with theories involving current-carrying edge excitations provides a potential explanation for the observed effects.
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