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Spectral Asymmetry Induces a Re-Entrant Quantum Hall Effect in a Topological Insulator.
Li-Xian Wang1,2, Wouter Beugeling1,2, Fabian Schmitt1,2
1Institute for Topological Insulators, Am Hubland, 97074, Würzburg, Germany.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|March 13, 2024
Summary
Researchers observed 2D Dirac physics in a 3D topological insulator, linking band inversion to the parity anomaly. This spectral asymmetry, evidenced by quantized Hall plateaus, occurs in a single topological surface state.
Area of Science:
- Condensed matter physics
- Quantum field theory
- Materials science
Background:
- Topological insulators exhibit unique surface states with Dirac fermion properties.
- The parity anomaly in 2D quantum field theory describes spectral asymmetry in massless Dirac fermions.
- This anomaly is theoretically linked to band inversion in 3D topological materials.
Purpose of the Study:
- To experimentally realize and investigate 2D Dirac physics and spectral asymmetry at the surface of a 3D topological insulator.
- To connect the observed phenomena to the parity anomaly and Landau level physics.
- To demonstrate the role of a single topological surface state in transport properties.
Main Methods:
- Utilized the 3D topological insulator (Hg,Mn)Te.
- Measured Hall resistance under finite magnetic fields.
- Analyzed quantized Hall plateau sequences for spectral asymmetry signatures.
Main Results:
- Observed an unconventional re-entrant sequence of quantized Hall plateaus.
- Directly related this sequence to spectral asymmetry in a single topological surface state.
- Confirmed the realization of 2D Dirac physics at the material's surface.
Conclusions:
- The parity anomaly manifests as spectral asymmetry in topological insulator surface states.
- This effect is observable in systems dominated by a single Dirac surface state.
- Experimental evidence supports the connection between band inversion and quantum field theory anomalies.
Keywords:
magnetotransportnarrow‐gap semiconductorsquantum Hall effectquantum anomaliestopological insulatorsMore Related Videos
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