4,871 research outputs found
Means for accommodating large overstrain in lead wires
An electrical wire is reported along whose length loops are formed at intervals and retained in a plastic capsule that allows unfolding of the loop when tension is exerted on the opposite ends of the wire. The capsule is formed by encompassing each loop with a sleeve of heat shrinkable synthetic plastic material which overlaps the loop and heat shrinking the overlapping portions. Thus, a length of electrical wire is formed which stores extra lengths of wire in the quantity needed to match the expected stretching of materials or elements such as ropes, cords and the like of high elongation to which the electrical wire may be attached
Strong Pinning Enhancement in MgB2 Using Very Small Dy2O3 Additions
0.5 to 5.0 wt.% Dy2O3 was in-situ reacted with Mg + B to form pinned MgB2.
While Tc remained largely unchanged, Jc was strongly enhanced. The best sample
(only 0.5 wt.% Dy2O3) had a Jc of 6.5 x 10^5 A/cm^2 at 6K, 1T and 3.5 x 10^5
A/cm^2 at 20K, 1T, around a factor of 4 higher compared to the pure sample, and
equivalent to hot-pressed or nano-Si added MgB2 at below 1T. Even distributions
of nano-scale precipitates of DyB4 and MgO were observed within the grains. The
room temperature resistivity decreased with Dy2O3 indicative of improved grain
connectivity.Comment: 13 pages, 4 figures and 1 tabl
Multiple layer local oxidation for fabricating semiconductor nanostructures
Coupled semiconductor nanostructures with a high degree of tunability are
fabricated using local oxidation with a scanning force microscope. Direct
oxidation of the GaAs surface of a Ga[Al]As heterostructure containing a
shallow two-dimensional electron gas is combined with the local oxidation of a
thin titanium film evaporated on top. A four-terminal quantum dot and a double
quantum dot system with integrated charge readout are realized. The structures
are tunable via in-plane gates formed by isolated regions in the electron gas
and by mutually isolated regions of the Ti film acting as top gates. Coulomb
blockade experiments demonstrate the high quality of this fabrication process.Comment: 3 pages, 3 figure
Time-Resolved Detection of Individual Electrons in a Quantum Dot
We present measurements on a quantum dot and a nearby, capacitively coupled,
quantum point contact used as a charge detector. With the dot being weakly
coupled to only a single reservoir, the transfer of individual electrons onto
and off the dot can be observed in real time in the current signal from the
quantum point contact. From these time-dependent traces, the quantum mechanical
coupling between dot and reservoir can be extracted quantitatively. A similar
analysis allows the determination of the occupation probability of the dot
states.Comment: 3 pages, 3 figure
Finite bias charge detection in a quantum dot
We present finite bias measurements on a quantum dot coupled capacitively to
a quantum point contact used as a charge detector. The transconductance signal
measured in the quantum point contact at finite dot bias shows structure which
allows us to determine the time-averaged charge on the dot in the non-blockaded
regime and to estimate the coupling of the dot to the leads.Comment: 6 pages, 4 figure
In Situ Treatment of a Scanning Gate Microscopy Tip
In scanning gate microscopy, where the tip of a scanning force microscope is
used as a movable gate to study electronic transport in nanostructures, the
shape and magnitude of the tip-induced potential are important for the
resolution and interpretation of the measurements. Contaminations picked up
during topography scans may significantly alter this potential. We present an
in situ high-field treatment of the tip that improves the tip-induced
potential. A quantum dot was used to measure the tip-induced potential.Comment: 3 pages, 1 figure, minor changes to fit published versio
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