5 research outputs found
Anomalous magnetotransport in wide quantum wells
We present magneto transport experiments of quasi 3D PbTe wide quantum wells.
A plateau-like structure in the Hall resistance is observed, which corresponds
to the Shubnikov de Haas oscillations in the same manner as known from the
quantum Hall effect. The onsets of plateaux in Rxy do not correspond to 2D
filling factors but coincide with the occupation of 3D (bulk-) Landau levels.
At the same time a non-local signal is observed which corresponds to the
structure in Rxx and Rxy and fulfils exactly the Onsager-Casimir relation
(Rij,kl(B) = Rkl,ij(-B)). We explain the behaviour in terms of edge channel
transport which is controlled by a permanent backscattering across a system of
"percolative EC - loops" in the bulk region. Long range potential fluctuations
with an amplitude of the order of the subband splitting are explained to play
an essential role in this electron system.Comment: postscript file including 3 figs, 5 page
Magnetotransport in wide parabolic PbTe quantum wells
The 3D- and 2D- behaviour of wide parabolic PbTe single quantum wells, which
consist of PbTe p-n-p-structures, are studied theoretically and experimentally.
A simple model combines the 2D- subband levels and the 3D-Landau levels in
order to calculate the density of states in a magnetic field perpendicular to
the 2D plane. It is shown that at a channel width of about 300nm on can expect
to observe 3D- and 2D-behaviour at the same time. Magnetotransport experiments
in selectively contacted Hall bar samples are performed at temperatures down to
T = 50 mK and at magnetic fields up to B = 17 T.Comment: postscript file including 2 figs, 4 pages, Paper presented at
EP2DS-XI, Nottingham 199
Conductance Fluctuations in PbTe Wide Parabolic Quantum Wells
We report on conductance fluctuations which are observed in local and
non-local magnetotransport experiments. Although the Hall bar samples are of
macroscopic size, the amplitude of the fluctuations from the local measurements
is close to e^2/h. It is shown that the fluctuations have to be attributed to
edge channel effects.Comment: postscript file including 3 figs, 3 pages, Paper presented at 3rd
Int. Symposium on "New Phenomena in Mesoscopic Structures" in Maui, Hawaii
199
Powder Bed Layer Characteristics: The Overseen First-Order Process Input
A discrete element powder model is used in conjunction with a finite volume melting model on the first layer of a powder bed selective laser melting process