78 research outputs found
Electron transport through antidot superlattices in heterostructures: new magnetoresistance resonances in lattices with large diameter antidots
In the present work we have investigated the transport properties in a number
of Si/SiGe samples with square antidot lattices of different periods. In
samples with lattice periods equal to 700 nm and 850 nm we have observed the
conventional low-field commensurability magnetoresistance peaks consistent with
the previous observations in GaAs/AlGaAs and Si/SiGe samples with antidot
lattices. In samples with a 600 nm lattice period a new series of
well-developed magnetoresistance oscillations has been found beyond the last
commensurability peak which are supposed to originate from periodic skipping
orbits encircling an antidot with a particular number of bounds.Comment: To appear in EuroPhys. Let
Transport properties of a 3D topological insulator based on a strained high mobility HgTe film
We investigated the magnetotransport properties of strained, 80nm thick HgTe
layers featuring a high mobility of mu =4x10^5 cm^2/Vs. By means of a top gate
the Fermi-energy is tuned from the valence band through the Dirac type surface
states into the conduction band. Magnetotransport measurements allow to
disentangle the different contributions of conduction band electrons, holes and
Dirac electrons to the conductivity. The results are are in line with previous
claims that strained HgTe is a topological insulator with a bulk gap of ~15meV
and gapless surface states.Comment: 11 pages (4 pages of main text, 6 pages of supplemental materials), 8
figure
Unconventional Hall effect near charge neutrality point in a two-dimensional electron-hole system
The transport properties of the two-dimensional system in HgTe-based quantum
wells containing simultaneously electrons and holes of low densities are
examined. The Hall resistance, as a function of perpendicular magnetic field,
reveals an unconventional behavior, different from the classical N-shaped
dependence typical for bipolar systems with electron-hole asymmetry. The
quantum features of magnetotransport are explained by means of numerical
calculation of the Landau level spectrum based on the Kane Hamiltonian. The
origin of the quantum Hall plateau {\sigma}xy = 0 near the charge neutrality
point is attributed to special features of Landau quantization in our system.Comment: 8 pages, 7 figure
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