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A particular subject of investigation is the role of several sadle-point contact (QPC) parameters on the scattering properties of an Aharonov–Bohm–Aharonov–Casher quantum ring (QR) under Rashba-type spin orbit interaction. We discuss the interplay of the conductance with the confinement strengths and height of the QPC, which yields new and tunable harmonic and non-harmonics patterns, while one manipulates these constriction parameters. This phenomenology may be of utility to implement a novel way to modulate spin interference effects in semiconducting QRs, providing an appealing test-platform for spintronics applications. [ABSTRACT FROM AUTHOR]

We present a theoretical procedure, which is fundamental for unitarity preservation in multicomponent–multiband systems, for a synchronous mixed-particle quantum transport. This study focuses the problem of (N × N) interacting components (with N ≥ 2), in the framework of the envelope function approximation (EFA), and the standard unitary properties of the (N = 1) scattering matrix are recovered. Rather arbitrary conditions to the basis-set and/or to the output scattering coefficients, are not longer required to preserve flux conservation, if the eigen -functions are orthonormalized in both the configuration and the spinorial spaces. We predict that the present approach, is valid for different kind of multiband–multicomponent physical systems of coupled charge–spin carriers, within the EFA, with small transformations if any. We foretell the interplay for the state-vector transfer matrix eigen -values, together with the large rates of its condition number, as novel complementary tools for a more accurate definition of the threshold for tunneling channels in a scattering experiment. • Unitarity for N –component mixed flux demands: complete-orthonormalized basis. • Symmetries for an arbitrary basis require: structured unitarity. • Matrix condition number, tunes threshold-energy for available tunneling channels. [ABSTRACT FROM AUTHOR]

An appropriate combination of the scattering theory and the transfer matrix formalism, for the solution of a (4×4) Kohn–Lu¨ttinger model, allow us to study the multichannel-multiband transmission process of heavy and light holes through a (GaAs/AlAs)n superlattice. Appealing effects and interesting channel coupling phenomena, mediated by quasi-bond states, are clearly foreseen. [Copyright &y& Elsevier]

Applying the well known symmetry requirements on the transfer matrices, more frequently used to study the energy spectra and the scattering properties of multiband systems, we show that the time reversal invariance and the parity symmetry in the (2×2) sub-spaces of the (4×4) Kohn–Lu¨ttinger model, taken separately, are broken as one moves away from the Brillouin Zone center. [Copyright &y& Elsevier]