Exploring interactions and coherent transport in 1D systems |
| Dr. Mike Lilly |
| Sandia National Lab |
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The observation of quantized conductance steps in
ballistic semiconductor quantum wires is an early example of the now
very broad field of nanoelectronics. Although the physics of plateaus at
quantized values of G0 = 2e2/h is easily
understood using non-interacting quantum mechanics, Coulomb interactions
are expected to play a key role in 1D systems. In this talk, transport
experiments on single and double quantum wires will be presented. In the
first part, the interplay between disorder and interactions in long
single wires and wires with a variable density will be tested with a
variety of conductance measurements. The second part of the talk focuses
on tunneling in a system of vertically coupled quantum wires. These
nanostructures are fabricated from bilayer electron samples with
electron beam lithography on both top and bottom defining the double
wire. Parallel conductance as a function of split gate voltages provide
a map of the 1D subband occupations; tunneling measurements can be made
with any combination of subbands occupied in each wire. The full
tunneling spectroscopy is measured using both a voltage between the
wires and a parallel magnetic field to learn about both the energy and
momentum dependence of tunneling events. We compare the data to a
non-interacting model of tunneling. Deviations from the simple picture
may require analysis of the 1D systems as Luttinger liquids. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000. |
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