Hole spectra and conductance for quantum wire systems under Rashba spin-orbit interaction

Focusing a problem with Rashba spin-orbit interaction (SOI-R), we propose an approach derived from standard multiband Hamiltonians that incorporate several hole band mixing effects. The influence of the SOI-R is shown on both the band structure and the zero-temperature conductance of a quasi-one-dimensional hole system patterned in a two-dimensional hole gas by a repulsive bias. The SOI-R leads the hole spectrum to split, as expected. However, we found appealing additional sub-band extremes only for heavy holes' unfolded sub-bands. The heavy-hole energy splitting exhibits a strong dependency on the wave vector component k(z) along the wire as well as on the effective Rashba parameter that clearly departs from the two-dimensional (2D) case. Nevertheless, for some low interval of k(z), the standard 2D feature is preserved and the splitting naturally follows a cubic proportionality. The two-probe Landauer ladder-steps quantization conductance shifts down to lower Fermi energies for nonzero SOI-R. The existence of heavy hole subband multiple minima lead to additional propagating modes and, thus, anomalous peaks for the ballistic conductance arise at variance with the opposite for light holes. The robustness of the anomalous features in the ballistic conductance can be tuned by manipulating the effective Rashba parameter and the hole-nanowire width, leading to destroy them as well. (C) 2011 American Institute of Physics. [doi:10.1063/1.3660213]