7,257 research outputs found
New physical principles of contact thermoelectric cooling
We suggest a new approach to the theory of the contact thermoelectric cooling
(Peltier effect). The metal-metal, metal-n-type semiconductor, metal-p-type
semiconductor, p-n junction contacts are analyzed. Both degenerate and
non-degenerate electron and hole gases are considered. The role of
recombination in the contact cooling effect is discussed by the first time.Comment: 8 pages, 8 figures, revtex
Magnetization dynamics of two interacting spins in an external magnetic field
The longitudinal relaxation time of the magnetization of a system of two
exchange coupled spins subjected to a strong magnetic field is calculated
exactly by averaging the stochastic Gilbert-Landau-Lifshitz equation for the
magnetization, i.e., the Langevin equation of the process, over its
realizations so reducing the problem to a system of linear
differential-recurrence relations for the statistical moments (averaged
spherical harmonics). The system is solved in the frequency domain by matrix
continued fractions yielding the complete solution of the two-spin problem in
external fields for all values of the damping and barrier height parameters.
The magnetization relaxation time extracted from the exact solution is compared
with the inverse relaxation rate from Langer's theory of the decay of
metastable states, which yields in the high barrier and intermediate-to-high
damping limits the asymptotic behaviour of the greatest relaxation time.Comment: 32 pages, 5 figures. The paper has been revised and new results added
(e.g., Fig. 5
Plasmonic shock waves and solitons in a nanoring
We apply the hydrodynamic theory of electron liquid to demonstrate that a
circularly polarized radiation induces the diamagnetic, helicity-sensitive dc
current in a ballistic nanoring. This current is dramatically enhanced in the
vicinity of plasmonic resonances. The resulting magnetic moment of the nanoring
represents a giant increase of the inverse Faraday effect. With increasing
radiation intensity, linear plasmonic excitations evolve into the strongly
non-linear plasma shock waves. These excitations produce a series of the well
resolved peaks at the THz frequencies. We demonstrate that the plasmonic wave
dispersion transforms the shock waves into solitons. The predicted effects
should enable multiple applications in a wide frequency range (from the
microwave to terahertz band) using optically controlled ultra low loss
electric, photonic and magnetic devices.Comment: 13 pages, 12 figure
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
Linear magnetoresistance in compensated graphene bilayer
We report a nonsaturating linear magnetoresistance in charge-compensated
bilayer graphene in a temperature range from 1.5 to 150 K. The observed linear
magnetoresistance disappears away from charge neutrality ruling out the
traditional explanation of the effect in terms of the classical random resistor
network model. We show that experimental results qualitatively agree with a
phenomenological two-fluid model taking into account electron-hole
recombination and finite-size sample geometry
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