Conformal Affine Toda Soliton and Moduli of IIB Superstring on AdS5×S5AdS_5\times S^5

In this paper we interpret the hidden symmetry of the moduli space of IIB superstring on $AdS_{5}\times S^{5}$ in terms of the chiral embedding in $AdS_{5}$, which turns to be the $\mathbb{CP}^{3}$ conformal affine Toda model. We review how the position $\mu$ of poles in the Riemann-Hilbert formulation of dressing transformation and how the value of loop parameters $\mu$ in the vertex operator of affine algebra determines the moduli space of the soliton solutions, which describes the moduli space of the Green-Schwarz superstring. We show also how this affine SU(4) symmetry affinize the conformal symmetry in the twistor space, and how a soliton string corresponds to a Robinson congruence with twist and dilation spin coefficients $\mu$ of twistor.Comment: Final version, Misprints corrected, Note adde

Crystal Field and Dzyaloshinsky-Moriya Interaction in orbitally ordered La_{0.95}Sr_{0.05}MnO_3: An ESR Study

We present a comprehensive analysis of Dzyaloshinsky-Moriya interaction and crystal-field parameters using the angular dependence of the paramagnetic resonance shift and linewidth in single crystals of La_{0.95}Sr_{0.05}MnO_3 within the orthorhombic Jahn-Teller distorted phase. The Dzyaloshinsky-Moriya interaction (~ 1K) results from the tilting of the MnO_6 octahedra against each other. The crystal-field parameters D and E are found to be of comparable magnitude (~ 1K) with D ~= -E. This indicates a strong mixing of the |3z^2-r^2> and |x^2-y^2> states for the real orbital configuration.Comment: 12 pages, 6 figure

Turbulent Thermalization

We study, analytically and with lattice simulations, the decay of coherent field oscillations and the subsequent thermalization of the resulting stochastic classical wave-field. The problem of reheating of the Universe after inflation constitutes our prime motivation and application of the results. We identify three different stages of these processes. During the initial stage of ``parametric resonance'', only a small fraction of the initial inflaton energy is transferred to fluctuations in the physically relevant case of sufficiently large couplings. A major fraction is transfered in the prompt regime of driven turbulence. The subsequent long stage of thermalization classifies as free turbulence. During the turbulent stages, the evolution of particle distribution functions is self-similar. We show that wave kinetic theory successfully describes the late stages of our lattice calculation. Our analytical results are general and give estimates of reheating time and temperature in terms of coupling constants and initial inflaton amplitude.Comment: 27 pages, 13 figure

Miniband-related 1.4–1.8 μm luminescence of Ge/Si quantum dot superlattices

The luminescence properties of highly strained, Sb-doped Ge/Si multi-layer heterostructures with incorporated Ge quantum dots (QDs) are studied. Calculations of the electronic band structure and luminescence measurements prove the existence of an electron miniband within the columns of the QDs. Miniband formation results in a conversion of the indirect to a quasi-direct excitons takes place. The optical transitions between electron states within the miniband and hole states within QDs are responsible for an intense luminescence in the 1.4–1.8 µm range, which is maintained up to room temperature. At 300 K, a light emitting diode based on such Ge/Si QD superlattices demonstrates an external quantum efficiency of 0.04% at a wavelength of 1.55 µm

A composite functional material with shape memory effect exhibiting a giant reversible straining

A new design principle of a composite functional material on the basis of a material with shape memory effect has been proposed and tested in experiment. This design can be applied to the majority of traditional materials with shape memory effect (ferromagnetic and non-ferromagnetic alloys as well as for polymers) and it provides in all cases a giant reversible straining though the "one-way" shape memory effect is used only. This design is especially promising for applications in the fields of micro- and nano-electromechanical systems.Запропоновано та експериментально випробувано нову схему композитного функціонального матеріалу на основі матеріалу з ефектом пам'яті форми. Ця схема може бути застосована для більшості традиційних матеріалів з пам'яттю форми - феромагнітних та неферомагнітних сплавів, а також полімерів. У всіх випадках вона забезпечує гігантську оборотну деформацію, хоч використовується лише "односторонній" ефект пам'яті форми. Ця схема є особливо перспективною для застосування у галузі мікрота наномеханіки.Предложена и экспериментально испытана новая схема композитного функционального материала на основе материала с эффектом памяти формы. Эта схема может быть применена для большинства традиционных материалов с памятью формы - ферромагнитных и неферромагнитных сплавов, а также полимеров. Во всех случаях она обеспечивает гигантскую обратимую деформацию, хотя используется только "односторонний эффект памяти формы". Эта схема особенно перспективна для применений в области микро- и наномеханики