BU Condensed Matter Seminar

[Claudio Chamon <chamon bu edu>]

BU Condensed Matter Seminar
Friday, Oct. 3, 11:00 am
Room SCI 352
Metcalf Science Center
590 Commonwealth Ave., Boston


 Dr. Matthew Grayson
 Walter Schottky Institut
 Technische Universitaet Muenchen
 Germany


"Corner quantum wells:  Quantum Hall physics in a two-dimensional electron
system bent by 90 degrees"


Abstract:
We demonstrate a new type of quantum confinement structure consisting of a
high-mobility GaAs/AlGaAs heterostructure overgrown on top of a precleaved
corner substrate.  The resulting corner-junction quantum-well
heterostructure (CQW) effectively bends a two-dimensional electron system
(2DES) at an atomically sharp 90 degree angle.  The 2DES exhibits the
fractional quantum Hall effect on both facets, attesting to its high
quality and enabling a set of new experiments on QHE edge systems to be
realized.  In tilted fields, we can measure equilibration between both co-
and counterpropagating edge channels of arbitrary filling factor.  With
counterpropagating edge channels of the same filling factor, we observe
anomalous Landauer-Buttiker reflection coefficients for both integer and
fractional edges when they traverse the corner.