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

Y Gul; G L Creeth; D English; S N Holmes; K J Thomas; I Farrer; D J Ellis; D A Ritchie; M Pepper

doi:10.1088/1361-648X/aafd05

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

J Phys Condens Matter. 2019 Mar 13;31(10):104002. doi: 10.1088/1361-648X/aafd05. Epub 2019 Jan 9.

Authors

Y Gul¹, G L Creeth, D English, S N Holmes, K J Thomas, I Farrer, D J Ellis, D A Ritchie, M Pepper

Affiliation

¹ London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom.

PMID: 30625452
DOI: 10.1088/1361-648X/aafd05

Abstract

We present electrical measurements from In_0.75Ga_0.25As 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 × (2e 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.