Quantum effects in linear and nonlinear transport of T-shaped ballistic junction patterned from GaAs/Al_ {x} Ga_ {1− x} As heterostructures

Physical review. B, Condensed matter (Impact Factor: 3.66). 06/2010; 81(23). DOI: 10.1103/PhysRevB.81.233306
Source: arXiv


We report low-temperature transport measurements of three-terminal T-shaped device patterned from GaAs/AlxGa1−xAs heterostructure. We demonstrate the mode branching and bend resistance effects predicted by numerical modeling for linear conductance data. We show also that the backscattering at the junction area depends on the wave function parity. We find evidence that in a nonlinear transport regime the voltage of floating electrode always increases as a function of push-pull polarization. Such anomalous effect occurs for the symmetric device, provided the applied voltage is less than the Fermi energy in equilibrium.

Download full-text


Available from: Krzysztof Fronc
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present studies of ballistic transport in three terminal T-shaped junction in a linear and non-linear regime. The floating electrode acts as a scatterer and modifies the conductance in a direct channel (between source and drain electrode). In the low voltage limit, the conductance shows the Wigner threshold effect and the bend resistance. A specific shape of the Wigner singularities can be changed by applied voltage to the floating electrode as well as by a shift of the Fermi level. The system also exhibits filtering properties with current distribution between different modes propagating in the junction. Back action of current flowing in the direct channel on changes of the voltage in the floating electrode is considered in the non-linear regime.
    Preview · Article · Dec 2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report the observation of the Fermi energy controlled redirection of the ballistic electron flow in a three-terminal system based on a small (100 nm) triangular quantum dot defined in a two-dimensional electron gas (2DEG). Measurement shows strong large-scale sign-changing oscillations of the partial conductance coefficient difference G(21) - G(23) on the gate voltage in zero magnetic field. Simple formulas and numerical simulation show that the effect can be explained by quantum interference and is associated with weak asymmetry of the dot or inequality of the ports connecting the dot to the 2DEG reservoirs. The effect may be strengthened by a weak perpendicular magnetic field. We also consider an additional three-terminal system in which the direction of the electron flow can be controlled by the voltage on the scanning gate microscopy (SGM) tip.
    Full-text · Article · Mar 2012 · Nanotechnology