Nonlinear magnetoconductance of nanowires

We calculate the conductance through a Gaussian impurity potential in a quantum wire using the Lippmann-Schwinger equation. The impurity has a decay length d along the propagation direction while it is localized along the transverse direction. In the case of a repulsive Gaussian impurity it is shown that the conductance quantization is strongly affected by the decay length. In particular, increasing d causes gradual suppression of backscattering and smaller contribution of evanescent modes, leading to progressively sharper conductance steps. The dependence of the conductance on the impurity position is also examined. In the case of an attractive Gaussian impurity it is shown that multiple quasibound states are formed due to the finite size of the impurity. By varying the size of the impurity these quasibound states may evolve into highly localized states with greatly enhanced lifetime. It is also shown ͑for a model impurity potential very similar to the Gaussian͒ that the transmission exhibits asymmetric Fano line shape. Under certain circumstances the Fano line shape may appear "inverted" or evolve into a Breit-Wigner dip. We consider also the effects of the cross-sectional shape of the wire on the quantum transmission. It is shown that varying the cross-sectional shape causes shifting of the positions of the conductance steps ͑which is due to the rearrangement of the transverse energy levels͒ and influences the character of conductance quantization.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Conductance of a quantum wire with a Gaussian impurity potential and variable cross-sectional shape

Vargiamidis

Polatoglou

2005

“…4 In addition, the conductance quantization is very sensitive to the boundary conditions at junctures of the wire with the electron reservoirs. 5 As was shown, [6][7][8] if the cross section varies with the length then the width of each plateau varies with .…”

Section: Introductionmentioning

confidence: 91%

Quantization of the conductance of a three-dimensional quantum wire in the presence of a magnetic field

Geyler

Margulis

2000

“…3 A variety of quantum effects have been discovered so far, such as conductance fluctuation, resonant tunnelling, nonlocality, Aharanov-Bohm effect, Kondo resonance, Coulomb blockade, trapped bound states, and nonlinear magnetoconductance. [4][5][6][7][8][9] These studies raise the possibility of radically new electronic devices with fascinating physics. Several nanodevices have been proposed, e.g., resonant tunnelling diodes, quantum transistors and switches, stub tuners, band filters, and Carbon nanotube quantum resistors ͑see Refs.…”

Section: Introductionmentioning

confidence: 99%

Quantum waveguide theory: A direct solution to the time-dependent Schrödinger equation

Wang

Midgley

1999

In this paper, we present a highly accurate and effective theoretical model to study electron transport and interference in quantum cavities with arbitrarily complex boundaries. Based on this model, a variety of quantum effects can be studied and quantified. In particular, this model provides information on the transient state of the system under study, which is important for analyzing nanometer-scale electronic devices such as high-speed quantum transistors and quantum switches. ͓S0163-1829͑99͒02739-3͔