Self-organised fractional quantisation in a hole quantum wire.

Area of Science:

• Quantum physics
• Condensed matter physics
• Semiconductor nanostructures

Background:

• Quantum wires exhibit quantized energy levels due to electrostatic confinement.
• Hole transport in strained germanium layers is crucial for advanced electronic devices.

Purpose of the Study:

• Investigate hole transport in strained germanium quantum wires.
• Characterize quantized conductance levels and their behavior under varying conditions.
• Explore evidence of fractional charge behavior.

Main Methods:

• Fabrication of strained germanium two-dimensional layers.
• Electrostatic confinement to form quantum wires.
• Ballistic conductance measurements at low temperatures.
• Application of strong parallel magnetic fields.

Main Results:

• Observed regular quantized conductance plateaus (n2e²/h) in ballistic transport.
• Detected new quantized plateaus (n=1/4, 1/8) at reduced carrier concentration and low temperatures.
• Identified a further plateau (n=1/32) unaffected by magnetic fields.
• Observed fractional charge behavior (e/2, e/4) indicated by quantized levels.

Conclusions:

• The formation of a zig-zag structure in quantum wires influences quantized levels.
• Evidence suggests fractionalization of charge carriers in the studied system.
• Further investigation into the mechanisms of fractional charge is warranted.