Conductance quantisation in patterned gate In_0.75Ga_0.25As structures up to 6  ×  (2e ²/h)

Area of Science:

• Semiconductor physics
• Condensed matter physics
• Materials science

Background:

• Spin-orbit coupling (SOC) is crucial for spintronic devices.
• Rashba-type SOC in 2D electron gases (2DEGs) is well-studied.
• Understanding SOC in lower-dimensional systems is key for future electronics.

Purpose of the Study:

• Investigate electrical transport in In0.75Ga0.25As 1D channels.
• Characterize the influence of Rashba-type SOC from 2D contacts on 1D transport.
• Determine the g-factor modification in the 1D channel due to SOC.

Main Methods:

• Fabrication of In0.75Ga0.25As 1D channel devices.
• Electrical measurements including source-drain voltage sweeps.
• Application of in-plane magnetic fields and asymmetric gate biasing.

Main Results:

• Observed enhanced ballistic transport with quantized conductance plateaus up to 6x(2e^2/h).
• Demonstrated suppressed backscattering at the 1D channel entrance due to time-reversal asymmetry.
• Measured a reduced g-factor of ~6.5 in the 1D channel, down from ~9 in 2D, under specific field orientations.

Conclusions:

• Rashba-type SOC in 2D contacts significantly impacts 1D channel transport.
• Ballistic transport is enhanced by suppressed backscattering.
• The g-factor reduction in the 1D channel is a direct consequence of the interplay between Rashba and applied magnetic fields.