Conductance quantisation in patterned gate In0.75Ga0.25As structures up to 6 × (2e 2/h)

We present electrical measurements from In0.75Ga0.25As 1-dimensional channel devices with Rashba-type, spin-orbit coupling present in the 2-dimensional contact regions. Suppressed backscattering as a result of the time-reversal asymmetry at the 1-dimensional channel entrance results in enhanced ballistic transport characteristics with clear quantised conductance plateaus up to 6×(2e2/h). Applying D.C. voltages between the source and drain ohmic contacts and an in-plane magnetic field confirms a ballistic transport picture. For asymmetric patterned gate biasing, a lateral spin-orbit coupling effect is weak. However, the Rashba-type spin-orbit coupling leads to a g-factor in the 1-dimensional channel that is reduced in magnitude from the 2-dimensional value of 9 to ~ 6.5 in the lowest subband when the effective Rashba field and the applied magnetic field are perpendicular.