A half-step in quantized conductance for low-density electrons in a quantum wire.

We investigated the effect of perpendicular magnetic field on quantum wires when the spin-orbit interaction (SOI) of electrons is not neglected. Based on the calculated energy dispersion, the nonlinear ballistic conductance (G) and electron-diffusion thermoelectric power (Sd) are calculated as functions of the electron density, temperature and applied bias voltage. A low-temperature half-step feature in G that was observed experimentally by Quay et al. [Nat. Phys. 6, 336 (2010)], as well as a new peak in Sd are reproduced here in the low density region. These phenomena are related to the occurrence of Zeeman splitting and a SOI induced saddle point in the band structure where the channel chemical potential lies within an anticrossing gap between the saddle point of the lower subband and the bottom of the upper subband. Additionally, side peaks in G that are far away from the zero bias for the nonlinear transport, as well as a quadratic bias-voltage dependence of G near zero voltage, are predicted and discussed. [ABSTRACT FROM AUTHOR]