Spin-wave resonance in a tangentially magnetized thin film

The imaginary part of the magnetic susceptibility determining the position, amplitude, and width of damped bulk and surface spin-wave eigenmodes in the spin system of a thin film magnetized in the film plane along the uniaxial bulk and surface anisotropy axis is analyzed numerically for various values of the degree of surface spin pinning. The presence of damping and the finiteness and asymmetry of the degree of surface spin pinning are shown to cause significant changes in the spin-wave resonance spectrum.     

Pulse dynamics in inhomogeneous optically coupled amplifying optical fibers with high-order dispersion effects taken into account

The evolution of the envelope of a two-mode wave packet in an inhomogeneous-over-length amplifying optical fiber is analyzed with the third-order dispersion effects taken into account, the presence of which leads to modulations of one or both edges of the wave packet. High degrees of compression of the pulse and the complete suppression of oscillations of its time envelope can be attained by an appropriate choice of the type of inhomogeneity of the dispersion parameters.     

Kinetics and products of the catalytic oxidation of acetamidotoluenes with ozone in acetic acid

The kinetics of acetamidotoluene oxidation in glacial acetic acid in the presence of cobalt acetate is reported. At 95°C and atmospheric pressure, acetamidotoluenes are oxidized by molecular oxygen very slowly: oxidation is complete in 10–12 h, and the major reaction products are acetamidobenzoic acids (27–36% yield). The introduction of ozone into the reactive gas increases the reaction rate by one order of magnitude. The main role of ozone is to generate the active form of the catalyst.     

Ferromagnetic resonance and bistability field in a uniaxial magnetic film

Peculiarities of ferromagnetic resonance (FMR) corresponding to bias along the “hard” magnetic axis of a film with 2D uniaxial anisotropy are studied based on numerical solution of magnetic moment dynamics equations. It is shown that an additional resonance peak is formed in the FMR spectrum in the vicinity of “bistability field” H _b . The dependence of this field on the amplitude of the microwave field and damping parameters is analyzed.     

Magnetization dynamics under nonlinear ferromagnetic resonance conditions in a (111) film

The equation of motion of magnetization of a garnet ferrite (111) film is solved numerically. It is shown that different regimes of the resonance precession of magnetization are realized depending on the bias and microwave fields; the regimes differ in amplitude and in the shape of their magnetization precession trajectories. In addition, bifurcations occur which lead to an abrupt change in amplitude, to bistability, and to precession with a period that is a multiple of the microwave-field period.     

Soliton pulses in two-mode periodic fibers

The conditions of the formation and the propagation of soliton pulses in a periodic two-mode non-linear fiber are studied. The analysis takes into account the dispersion of a fiber material and the intermode dispersion of the interacting modes subject to the conditions of their phase matching.     

Dispersion of Electromagnetic Waves in a Periodic Ferromagnet-Dielectric Structure

The special features of normal TE mode propagation in a periodic ferromagnet-dielectric structure are investigated. The magnetizing field is parallel to the boundary between the media and perpendicular to the mode propagation direction. The matrix of the structure period transformation, dispersion relation, and energy reflection coefficient are derived by solving the boundary problem for the normal wave incidence on a semi-infinite periodic medium. It is demonstrated that the reflected wave spectrum and characteristics can be controlled by an external field. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 69–75, May, 2005.     

Pulse dynamics in an optical fiber with linear intermode coupling and Kerr nonlinearity dispersion

The effect of Kerr nonlinearity dispersion on the envelope duration and the velocity of the envelope maximum for a wave packet propagating in an optical fiber and formed by two coupled copropagating waves is studied. The critical (threshold) energy of wave packet collapse can substantially be diminished and the supraluminal mode of propagation of the pulse envelope maximum in a nonamplifying medium can be realized owing to a significantly higher nonlinearity dispersion in such systems in comparison with “single-wave” ones.     

Modulation instability of wave packets in the presence of linear and nonlinear mode coupling

Conditions for modulation instability of a wave packet consisting of two codirected linearly coupled waves propagating in a light guide with Kerr-type nonlinearity are formulated. The development of the instability with regard to light guide parameters, linear and nonlinear mode coupling, and input power is analyzed for symmetric and antisymmetric light guide excitations. Unlike in single-mode light guides, here modulation instability may arise in the frequency ranges of normal material dispersion and at the zero perturbation frequency.     

Dynamic orientational phase transition in a two-layer magnetically coupled structure

The magnetization dynamics was studied for a system of two magnetic layers separated by a nonmagnetic spacer providing their antiferromagnetic coupling. A new effect of orientational phase transition occurring upon a change in the amplitude (frequency) of a microwave field was observed near the edge of the orientational hysteresis loop.