73,515 research outputs found
Giant dispersion of critical currents in superconductor with fractal clusters of a normal phase
The influence of fractal clusters of a normal phase on the dynamics of a
magnetic flux trapped in a percolative superconductor is considered. The
critical current distribution and the current-voltage characteristics of
fractal superconducting structures in the resistive state are obtained for an
arbitrary fractal dimension of the cluster boundaries. The range of fractal
dimensions, where the dispersion of critical currents becomes infinite, is
found. It is revealed that the fractality of clusters depresses of the electric
field caused by the magnetic flux motion thus increasing the critical current
value. It is expected that the maximum current-carrying capability of a
superconductor can be achieved in the region of giant dispersion of critical
currents.Comment: 7 pages with 3 figure
Correlators of the Kazakov-Migdal Model
We derive loop equations for the one-link correlators of gauge and scalar
fields in the Kazakov-Migdal model. These equations determine the solution of
the model in the large N limit and are similar to analogous equations for the
Hermitean two-matrix model. We give an explicit solution of the equations for
the case of a Gaussian, quadratic potential. We also show how similar
calculations in a non-Gaussian case reduce to purely algebraic equations.Comment: 14 pages, ITEP-YM-3-9
The Nature of Thermopower in Bipolar Semiconductors
The thermoemf in bipolar semiconductors is calculated. It is shown that it is
necessary to take into account the nonequilibrium distribution of electron and
hole concentrations (Fermi quasilevels of the electrons and holes). We find
that electron and hole electric conductivities of contacts of semiconductor
samples with connecting wires make a substantial contribution to thermoemf.Comment: 17 pages, RevTeX 3.0 macro packag
Radiative activity of magnetic white dwarf undergoing Lorentz-force-driven torsional vibrations
We study radiative activity of magnetic white dwarf undergoing torsional
vibrations about axis of its own dipole magnetic moment under the action of
Lorentz restoring force. It is shown that pulsating white dwarf can convert its
vibration energy into the energy of magneto-dipole emission, oscillating with
the frequency equal to the frequency of Alfv\'en torsional vibrations, provided
that internal magnetic field is decayed. The most conspicuous feature of the
vibration energy powered radiation in question is the lengthening of periods of
oscillating emission; the rate of period elongation is determined by the rate
magnetic field decay.Comment: Mod. Phys. Lett. A 26 (2011) 359-36
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