Conductance quantisation in patterned gate In 0.75 Ga 0.25 As structures up to 6 × (2 e 2 / h )

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We present electrical measurements from In 0.75 Ga 0.25 As 1D channel devices with Rashba-type, spin–orbit coupling present in the 2D contact regions. Suppressed backscattering as a result of the time-reversal asymmetry at the 1D channel entrance results in enhanced ballistic transport characteristics with clear quantised conductance plateaus up to 6 × (2 e 2 / h ). Applying DC 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 1D channel that is reduced in magnitude from the 2D value of 9 to ~6.5 in the lowest subband when the effective Rashba field and the applied magnetic field are perpendicular.