103,500 research outputs found
Binomial coefficients, Catalan numbers and Lucas quotients
Let be an odd prime and let be integers with and . In this paper we determine
mod for ; for example,
where is the Jacobi symbol, and is the Lucas
sequence given by , and for
. As an application, we determine modulo for any integer , where denotes the
Catalan number . We also pose some related conjectures.Comment: 24 pages. Correct few typo
Coulomb blockade in a Si channel gated by an Al single-electron transistor
We incorporate an Al-AlO_x-Al single-electron transistor as the gate of a
narrow (~100 nm) metal-oxide-semiconductor field-effect transistor (MOSFET).
Near the MOSFET channel conductance threshold, we observe oscillations in the
conductance associated with Coulomb blockade in the channel, revealing the
formation of a Si single-electron transistor. Abrupt steps present in sweeps of
the Al transistor conductance versus gate voltage are correlated with
single-electron charging events in the Si transistor, and vice versa. Analysis
of these correlations using a simple electrostatic model demonstrates that the
two single-electron transistor islands are closely aligned, with an
inter-island capacitance approximately equal to 1/3 of the total capacitance of
the Si transistor island, indicating that the Si transistor is strongly coupled
to the Al transistor.Comment: 3 pages, 4 figures, 1 table; typos corrected, minor clarifications
added; published in AP
Proximity and anomalous field-effect characteristics in double-wall carbon nanotubes
Proximity effect on field-effect characteristic (FEC) in double-wall carbon
nanotubes (DWCNTs) is investigated. In a semiconductor-metal (S-M) DWCNT, the
penetration of electron wavefunctions in the metallic shell to the
semiconducting shell turns the original semiconducting tube into a metal with a
non-zero local density of states at the Fermi level. By using a two-band
tight-binding model on a ladder of two legs, it is demonstrated that anomalous
FEC observed in so-called S-M type DWCNTs can be fully understood by the
proximity effect of metallic phases.Comment: 4 pages, 4 figure
Magnetization reversal through synchronization with a microwave
Based on the Landau-Lifshitz-Gilbert equation, it can be shown that a
circularly-polarized microwave can reverse the magnetization of a Stoner
particle through synchronization. In comparison with magnetization reversal
induced by a static magnetic field, it can be shown that when a proper
microwave frequency is used the minimal switching field is much smaller than
that of precessional magnetization reversal. A microwave needs only to overcome
the energy dissipation of a Stoner particle in order to reverse magnetization
unlike the conventional method with a static magnetic field where the switching
field must be of the order of magnetic anisotropy.Comment: 4 pages, 5 figure
Application of the 'ESCIMO' theory to turbulent diffusion flames
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A Millikelvin Scanned Probe for Measurement of Nanostructures
We demonstrate a scanning force microscope, based upon a quartz tuning fork,
that operates below 100 mK and in magnetic fields up to 6 T. The microscope has
a conducting tip for electrical probing of nanostructures of interest, and it
incorporates a low noise cryogenic amplifier to measure both the vibrations of
the tuning fork and the electrical signals from the nanostructures. At
millikelvin temperatures the imaging resolution is below 1 um in a 22 um x 22
um range, and a coarse motion provides translations of a few mm. This scanned
probe is useful for high bandwidth measurement of many high impedance
nanostructures on a single sample. We show data locating an SET within an array
and measure its coulomb blockade with a sensitivity of 2.6 x 10^-5 e/Hz^1/2.Comment: 5 pages, 5 figures, submitted to RS
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