Split-Channel Ballistic Transport in an InSb Nanowire

Area of Science:

• Condensed Matter Physics
• Nanoscience and Nanotechnology
• Semiconductor Physics

Background:

• One-dimensional (1D) electronic transport is crucial for future nanoelectronic devices.
• Understanding quantum phenomena in 1D systems like nanowires is key to advancing quantum technologies.

Purpose of the Study:

• To experimentally investigate 1D electronic transport in an Indium Antimonide (InSb) semiconducting nanowire.
• To explore the effects of local depletion using multiple bottom gates on quantum point contact formation and conductance quantization.
• To analyze the influence of magnetic fields and gate voltage configurations on 1D sub-band properties, including Zeeman splitting and degeneracy.

Main Methods:

• Fabrication and characterization of an InSb semiconducting nanowire.
• Utilizing three bottom gates for local depletion and creation of a ballistic quantum point contact.
• Applying magnetic fields and varying gate voltages to measure conductance.
• Analyzing conductance plateaus and resonant states to probe 1D sub-band structure.

Main Results:

• Observed conductance plateaus at multiples of e²/h in a magnetic field, indicating Zeeman splitting.
• Demonstrated tunable quantized conductance patterns dependent on gate voltage configurations.
• Showcased the disappearance of the first conductance plateau, revealing a 2-fold sub-band degeneracy persisting up to several tesla.
• Identified discrete resonant states and conductance features potentially related to helical gap formation.

Conclusions:

• The experimental findings are explained by the formation of two spatially separated 1D conduction channels within the InSb nanowire.
• Gate-controlled manipulation of 1D sub-band degeneracy and conductance is achievable.
• The study provides insights into the fundamental physics of electron transport in low-dimensional semiconductor systems.