684 research outputs found
Polarization dependent Landau level crossing in a two-dimensional electron system in MgZnO/ZnO-heterostructure
We report electrical transport measurements in a tilted magnetic field on a
high-mobility two-dimensional electron system confined at the MgZnO/ZnO
heterointerface. The observation of multiple crossing events of spin-resolved
Landau levels (LLs) enables the mapping of the sequence of electronic states.
We further measure the renormalization of electron spin susceptibility at zero
field and the susceptibility dependence on the electron spin polarization. The
latter manifests the deviation from the Pauli spin susceptibility. As the
result, the crossing of spin-resolved LLs shifts to smaller tilt angles and the
first Landau level coincidence event is absent even when the magnetic field has
only a perpendicular component to the 2DES plane.Comment: 5 pages, 4 figure
The direct synthesis of tertiary amines with three different substituents via the reaction of primary amines, alkyl halides, and alpha-chlorine substituted allylsilanes catalyzed by Lewis acids
ArticleTetrahedron Letters. 46(27): 4527-4530 (2005)journal articl
Nonlinear response of a MgZnO/ZnO heterostructure close to zero bias
We report on magnetotransport properties of a MgZnO/ZnO heterostructure
subjected to weak direct currents. We find that in the regime of overlapping
Landau levels, the differential resistivity acquires a quantum correction
proportional to both the square of the current and the Dingle factor. The
analysis shows that the correction to the differential resistivity is dominated
by a current-induced modification of the electron distribution function and
allows us to access both quantum and inelastic scattering rates.Comment: 4 pages, 3 figure
Fermi surface and superconductivity in low-density high-mobility {\delta}-doped SrTiO3
The electronic structure of low-density n-type SrTiO3 delta-doped
heterostructures is investigated by angular dependent Shubnikov-de Haas
oscillations. In addition to a controllable crossover from a three- to
two-dimensional Fermi surface, clear beating patterns for decreasing dopant
layer thicknesses are found. These indicate the lifting of the degeneracy of
the conduction band due to subband quantization in the two-dimensional limit.
Analysis of the temperature-dependent oscillations shows that similar effective
masses are found for all components, associated with the splitting of the light
electron pocket. The dimensionality crossover in the superconducting state is
found to be distinct from the normal state, resulting in a rich phase diagram
as a function of dopant layer thickness.Comment: 4 pages, 5 figures, submitted for publicatio
Temperature Dependent Polarity Reversal in Au/Nb:SrTiO3 Schottky Junctions
We have observed temperature-dependent reversal of the rectifying polarity in
Au/Nb:SrTiO3 Schottky junctions. By simulating current-voltage characteristics
we have found that the permittivity of SrTiO3 near the interface exhibits
temperature dependence opposite to that observed in the bulk, significantly
reducing the barrier width. At low temperature, tunneling current dominates the
junction transport due both to such barrier narrowing and to suppressed thermal
excitations. The present results demonstrate that novel junction properties can
be induced by the interface permittivity
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