Understanding the anomalous conductance plateau in asymmetrically biased InAs/In 0.52 Al 0.48 As quantum point contacts-A step towards a tunable all electric spin valve

• Published in: Applied physics letters Vol. 99; no. 12; pp. 122105 - 122105-3
• Main Authors: Das, P. P., Chetry, K. B., Bhandari, N., Wan, J., Cahay, M., Newrock, R. S., Herbert, S. T.
• Format: Journal Article
• Published: American Institute of Physics 21-09-2011
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.3636413

The appearance and evolution of an anomalous conductance plateau at 0.4(
2e
2
/h
) in an In
0.52
Al
0.48
As/InAs quantum point contact (QPC), in the presence of lateral spin-orbit coupling, has been studied at
T
=4.2 K as a function of the potential asymmetry between the in-plane gates of the QPC. The anomalous plateau, a signature of spin polarization in the channel, appears only over an intermediate range (around 3 V) of bias asymmetry. It is quite robust, being observed over a maximum range of nearly 1 V of the sweep voltage common to the two in-plane gates. The conductance measurements show evidence of surface roughness and dangling bond scattering from the side walls of the QPC.