186 research outputs found
Hysteresis of static polarizability of a ballistic ring in presence of intense high-frequency field
A ballistic ring in presence of collinear dc and high-frequency electric
fields is considered. A possibility is demonstrated of the system switching
between two states by changing the strength of dc and/or high-frequency field.
It leads to hysteretic behavior of the ring dc dipole moment as a function of
the dc electric field.Comment: 3 pages, 1 figur
Quasi-one-dimensional ballistic ring in crossed high-frequency electric fields
We study electron dynamics in a quasi-one-dimensional ballistic ring driven
by two crossed high-frequency electric fields parallel to the ring plane. The
averaged dipole moment and emission intensity are calculated. The emission
polarization coincides with the direction of one of the fields. A possibility
is shown of the polarization switching to perpendicular direction under changes
in the field amplitudes and frequencies.Comment: 7 pages, 2 figure
Quasi-one-dimensional ballistic ring in the field of circularly polarized electromagnetic wave
Dynamics is studied of an electron in a quasi-one-dimensional ballistic ring
under circularly polarized electromagnetic field propagating along the normal
to the ring plane. The average emission intensity from the ring is calculated.
The value and direction of the electron average angular velocity in the ring
depend on the incident wave parameters. It is found that the ring average
dipole moment can remain constant under certain conditions. Possibility is
shown of higher harmonics enhancement in the ring radiation spectrum.Comment: 8 pages, 6 figure
Stochastic resonance in a quasi-two-dimensional superlattice. II
A fluctuation theory is presented for the nonequilibrium second order phase
transition in a quasi-two-dimensional electron gas. A transverse (with respect
to the current through the sample) spontaneous electric field as an order
parameter and a driving longitudinal field as a control parameter are used. In
addition to the earlier results, the intrawell dynamics is taken into account.
Non-monotonous behavior of the periodic signal gain as a function of the noise
power (stochastic resonance) is predicted.Comment: 9 pages, 2 figure
Nonequilibrium phase transitions in a quasi-two-dimensional superlattice with parabolic miniband
Distribution function and current density in a one-dimensional superlattice
with parabolic miniband are calculated. The current dependence on the
temperature coincides with experimental data. Generalization is carried out to
quasi-two-dimensional superlattice with paraboloidal miniband. For a sample
opened in Y direction with dc current in X direction, a novel nonequilibrium
phase transition is found, namely, appearing a spontaneous transverse electric
field under temperature rising.Comment: 9 pages, 6 figure
Conductivity of a superlattice with parabolic miniband
The static and high-frequency differential conductivity of a one-dimensional
superlattice with parabolic miniband, in which the dispersion law is assumed to
be parabolic up to the Brillouin zone edge, are investigated theoretically.
Unlike the earlier published works, devoted to this problem, the novel formula
for the static current density contains temperature dependence, which leads to
the current maximum shift to the low field side with increasing temperature.
The high-frequency differential conductivity response properties including the
temperature dependence is examined and opportunities of creating a terahertz
oscillator on Bloch electron oscillations in such superlattices are discussed.
Analysis shows that superlattices with parabolic miniband dispersion law may be
used for generation and amplification of terahertz fields only at very low
temperatures.Comment: 10 pages, 5 figure
Current oscillations in a superlattice under non-quantizing electric and magnetic fields
We calculate the current density in a semiconductor superlattice with
parabolic miniband under crossed non-quantizing electric and magnetic fields.
The Corbino disk geometry is considered. The current-voltage curve contains
oscillations with period proportional to the magnetic field. The possibility is
shown of the negative absolute conductivity. The Ampere-Gauss characteristics
also contain overshoots under high enough electric fields. In all cases, the
peaks smear with temperature rising.Comment: 8 pages, 4 figure
Vibrational resonance in narrow-band conductors
The response is studied of a narrow-band conductor with bcc lattice to a
low-frequency signal under presence of a high-frequency signal. In a high
enough dc electric field Ex, the conduction electrons form a bistable system,
which results in spontaneous appearance of a transverse electric field Ey. Ac
field along y axis leads to amplification of the low-frequency signal with
non-monotonous dependence of the gain on the high-frequency field amplitude, so
that vibrational resonance takes place. Besides, high-frequency field induced
nonequilibrium phase transition is found.Comment: 5 pages, 5 figure
Double stochastic resonance in conductors with narrow conduction band
Results are presented of studying the stochastic resonance (SR) in conductors
with bcc lattice and narrow conduction band. In such materials, SR has a
feature, namely, the weak-signal gain as a function of the additive and
non-correlated noise level can have two maxima, i.e., double SR takes place.Comment: 2 pages, 2 figure
On the second harmonic generation in superlattices
In present work, we investigate the second harmonic generation in a
superlattice under presence of the carrier density gradient. We show that the
second harmonic intensity can be comparable with that of the current
fundamental harmonic in that case.Comment: 10 pages, 3 figure
- …