Vol 103, No 8 (2016)

A new nonlinear optical phenomenon—generation of surface waves by a drag current appearing at an inclined incidence of a focused femtosecond laser pulse—has been theoretically described. The generated waves have terahertz frequencies and their total energy increases with an increase in the effective frequency of electron–electron collisions and with a decrease in their density.

Combined dielectric/metal resonators for colossal enhancement of inelastic light scattering are developed and their properties are investigated. It is shown that a record enhancement factor of 2 × 10⁸ can be obtained using these structures. The dielectric resonators are fabricated on Si/SiO₂ substrates where periodic arrays of square 10- to 200-nm-high dielectric pillars are produced via electron-beam lithography and plasma etching. The lateral size a of the pillars varies between 50 and 1500 nm, and their period in the array is 2a. To make a combined dielectric/metal resonator, a nanostructured layer of silver is deposited onto the fabricated periodic dielectric structure by thermal evaporation. It is established that, for a fixed height of the dielectric pillars, the Raman scattering enhancement factor experiences pronounced oscillations as a function of the period (and size) of the pillars. It is shown that these oscillations are determined by the modes of the dielectric resonator and governed by the relation between the excitation laser wavelength and the planar size of the dielectric pillars.

Precise measurements of the magnetic-field and gate-voltage dependences of the capacitance of a field-effect transistor with an electron system in a wide GaAs quantum well have been carried out. It has been found that the capacitance minima caused by the gaps in the Landau spectrum of the electron system become anomalously wide when two size-quantization subbands are occupied. The effect is explained by retention of the chemical potential in the gap between the Landau levels of one of the subbands owing to redistribution of electrons between the subbands under a change in the magnetic field. The calculation taking into account this redistribution has been performed in a model of the electron system formed by two two-dimensional electron layers. The calculation results describe both the wide capacitance features and the observed disappearance of certain quantum Hall effect states.

A layer of an easy-axis antiferromagnet with antisymmetry center is considered. It is shown that the combination of magneto- and electric-dipole mechanisms of the indirect spin–spin interactions gives rise to the previously unknown class of hybrid dipole waves such as exchangeless magnetoelectric magnons and to the spin–spin and spin–dipole resonances accompanying them. The conditions for the formation of these waves are determined.

We analyze the influence of a dissipative environment on geometric phases in a quantum system subject to non-adiabatic evolution. We find dissipative contributions to the acquired phase and modification of dephasing, considering the cases of both weak short-correlated noise and slow quasi-stationary noise. Motivated by recent experiments, we find the leading non-adiabatic corrections to the results, known for the adiabatic limit.

A method for determining the degree of synchronization of intermittent phase synchronization regime from a time series has been proposed on the basis of estimating the zero conditional Lyapunov exponent. The efficiency of the method has been tested on model systems near the boundary of the appearance of the synchronous regime. The method has been used to determine the degree of synchronization between various regions of the brain of rats of the WAG/Rij line having a genetic predisposition to epilepsy.

The destruction of liquid tin at the extremely high strain rate caused by femtosecond laser pulses has been studied. The ablation and cavitation thresholds, as well as tensile stresses responsible for the destruction of liquid tin at a strain rate of ∼10⁹ s^–1, have been experimentally determined.