1,170 research outputs found
Strong vortex-antivortex fluctuations in the type II superconducting film
The small size vortex-antivortex pairs proliferation in type II
superconducting film is considered for the wide interval of temperatures below
Tc. The corresponding contribution to free energy is calculated. It is shown
that these fluctuations give the main contribution to the heat capacity of the
film both at low temperatures and in the vicinity of transition
How the Phase Slips in a Current-Biased Narrow Superconducting Stripe?
The theory of current transport in a narrow superconducting channel
accounting for thermal fluctuations is revisited. The value of voltage
appearing in the sample is found as the function of temperature (close to
transition temperature ) and bias
current ( is a value of critical current
calculated in the framework of the BCS approximation, neglecting thermal
fluctuations). It is shown that the careful analysis of vortex crossing of the
stripe results in considerable increase of the activation energy.Comment: 6 pages, 2 figure
Flat Thomas-Fermi artificial atoms
We consider two-dimensional (2D) "artificial atoms" confined by an axially
symmetric potential . Such configurations arise in circular quantum
dots and other systems effectively restricted to a 2D layer. Using the
semiclassical method, we present the first fully self-consistent and analytic
solution yielding equations describing the density distribution, energy, and
other quantities for any form of and an arbitrary number of confined
particles. An essential and nontrivial aspect of the problem is that the 2D
density of states must be properly combined with 3D electrostatics. The
solution turns out to have a universal form, with scaling parameters
and ( is the dot radius and is the effective
Bohr radius)
Massive liquid Ar and Xe detectors for direct Dark Matter searches
A novel experiment for direct searches of the Dark Matter with liquid argon
double-phase chamber with a mass of liquid Ar up to several hundred tons is
proposed. To suppress the b-, g- and n0- backgrounds, the comparison of
scintillation and ionization signals for every event is suggested. The addition
in liquid Ar of photosensitive Ge(CH3)4 or C2H4 and suppression of triplet
component of scintillation signals ensures the detection of scintillation
signals with high efficiency and provides a complete suppression of the
electron background. For the detection of photoelectrons and ionization
electrons, highly stable and reliable GEM detectors must be used.Comment: 8 pages, 2 figures, 1 tabl
Nuclear magnetic susceptibility of metals with magnetic impurities
We consider the contribution of magnetic impurities to the nuclear magnetic
susceptibility and to the specific heat of a metal. The impurity
contribution to the magnetic susceptibility has a behaviour, and the
impurity contribution to the specific heat has a behaviour, both in an
extended region of temperatures . In the case of a dirty metal the RKKY
interaction of nuclear spins and impurity spins is suppressed for low
temperatures and the main contribution to and is given by their
dipole-dipole interaction.Comment: 9 pages, 4 figures, REVTE
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