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

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

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