Quantized conductance through an asymmetric narrow constriction in a three-dimensional electron gas

Abstract

Quantized conductance through an asymmetric narrow constriction in a three-dimensional electron gas Waalkens, Holger CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date: 12-05-2018Quantized conductance through an asymmetric narrow constriction in a three-dimensional electron gas The quantized ballistic transmission of a three-dimensional electron gas through a narrow constriction modeled by an asymmetric hyperboloid is studied. The conductance as a function of voltage jumps by integer multiples of e 2 / ͑ប͒ each time a new transition channel opens in the plane of narrowest restriction, which has the shape of an ellipse. There are two different modes ͑"whispering gallery modes" and "bouncing ball modes"͒ which lead to different conductance steps. The smoothing of the conductance steps is discussed in terms of phase space tunneling through a dynamical barrier. A comprehensive interpretation of the quantum mechanical results is obtained from relating them to the corresponding classical motions.

Magnetoresistance anomalies resulting from Stark resonances in semiconductor nanowires with a constriction

“…In figure 3(b), we can identify the MR jumps at V ≃ 10, 20, 50, 90, and 140 mV. The rapid increase of MR at some drain-source voltage values is a direct consequence of the singularity in (17), which takes place when the differential conductance for B = 0 approaches zero.…”

“…The influence of the constriction shape on the conductance quantization was considered within the generalized Landauer-Büttkier formalism by Scherbakov et al [16], who demonstrated that the character of conductance quantization significantly depends on the asymmetry of the cross section and the softness of the confinement potential. A comprehensive analysis of this problem has been presented in [17]. The effect of quantum interference caused by the single point-like impurity or a couple of impurities localized in the constriction has been a subject of papers by Avotina et al [18,19].…”

Classical and quantum transport through entropic barriers modeled by hardwall hyperboloidal constrictions

“…From (20) and noting that n ¼ adnðk; qÞ=cnðk; qÞ we see that r ¼ aq0tnðk; qÞ is proportional to x and this is the motivation for the transformation (141). The scaling of the wavefunction (142) is performed in order to again obtain a system of type ''kinetic-plus-potential".…”

“…The quantum transmission problem (without resonances) through a constriction of the type (2) has been studied by Yosefin and Kaveh [18]. Similarly, the transmission problem (again without resonances) has been studied for an axially symmetric hyperboloidal constriction in 3D by Torres, Pascual and Sáenz [19], and for the asymmetric case by Waalkens [20]. The main purpose of the present paper is to study the quantum transmission and the assoicated resonances through the 2D and 3D constrictions (2) and (4) in a coherent way using the perspective of transition state theory.…”

Transition from positive to negative magnetoresistance induced by a constriction in semiconductor nanowire

“…24 Besides, the quantization of the conductance in the nanosystems has been experimentally confirmed more recently, 25 although this quantum effect in the 3D nanowires has been predicted much earlier. [26][27][28] The quantization of the conductance is difficult to observe in the real nanowires due to the presence of structural and substitutional disorder, and because of the boundary roughness. 25 This stems from the fact that scattering of conduction electrons on impurities or on structural imperfections results in the change of momentum (the momentum relaxation), which leads to smearing of the step-like form of the electric conductance.…”