Nondegenerate Integer Quantum Hall Effect from Topological Surface States in Ag₂Te Nanoplates

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• The quantum Hall effect is a key property of Dirac Fermions in topological insulators, leading to quantized electron transport.
• Achieving the quantum Hall effect with nondegenerate Dirac surface states has been a significant challenge in condensed matter physics.

Purpose of the Study:

• To demonstrate the nondegenerate integer quantum Hall effect from topological surface states in 3D topological insulator nanostructures.
• To investigate the role of structure inversion asymmetry (SIA) in lifting the degeneracy of Dirac surface states.

Main Methods:

• Fabrication and characterization of β-Ag2Te nanostructures.
• Measurement of electrical and thermal transport properties under magnetic fields, including tilted fields.
• Analysis of surface-state dominant conductance and thermopower behaviors.

Main Results:

• Observation of quantum Hall conductance plateaus with steps of e^2/h, characteristic of 2D massless Dirac electrons.
• Confirmation of the 2D nature of topological surface states through transport responses under tilted magnetic fields.
• Evidence of SIA-induced removal of surface state degeneracy, leading to a nondegenerate integer quantum Hall effect.

Conclusions:

• The study successfully demonstrates the nondegenerate integer quantum Hall effect in β-Ag2Te nanostructures, attributed to SIA lifting surface state degeneracy.
• These findings advance the fundamental understanding of Dirac Fermions in topological insulators.
• The results pave the way for potential applications in topological magneto-electric effects.