ELECTRONIC CONDUCTANCE IN MESOSCOPIC SYSTEMS - MULTICHANNEL QUANTUM SCATTERING CALCULATIONS

Multichannel quantum scattering theory is employed to calculate the no n-linear two-port conductance and magnetoconductance of mesoscopic sys tems such as quantum well heterostructures, quantum dots and semicondu ctor or metallic microstructures. We employ a specially designed stabl e invariant embedding technique for calculating reflection and transmi ssion amplitudes for these types of structure using a quantum rearrang ement scattering formulation. The method can be applied to calculate e lectronic transport in many types of system in the low-temperature reg ime where phonon scattering is not significant. The basis set used for the degrees of freedom orthogonal to the current flow can be adiabati c (i.e. dependent on the coordinate along the current Bow) or diabatic (not dependent on the coordinate). The dangers inherent in transformi ng an adiabatic formulation to a diabatic formulation with a limited b asis set size are forcefully illustrated. The method naturally include s closed-channel effects and can incorporate complex potentials (to si mulate decay). Examples are presented, wherein we calculate the conduc tance and magnetoconductance as a function of system geometry, electro nic potential and potential drop across two-dimensional quantum well h eterostrucrures, and the results are explained in simple physical term s. The resonance features in the non-linear conductance as functions o f magnetic field and of orifice width in heterostructure devices are d escribed and elucidated.