Anomalous thermopower in heavy-fermion compounds CeB<Subscript>6</Subscript>, CeAl<Subscript>3</Subscript>, and CeCu<Subscript>6 − <Emphasis Type="Italic">x</Emphasis></Subscript>Au<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>

High-precision measurements of thermopower have been performed in a wide temperature range (2–300 K) for a series of cerium-based heavy-fermion compounds, including CeB₆, CeAl₃, CeCu₆, and substitutional solid solutions of the CeCu_{6 ? x} Au _x system (x = 0.1, 0.2). All compounds exhibit an unusual (logarithmic) asymptotic behavior of the temperature dependence of the Seebeck coefficient: S ∝ ?lnT. In the case of cerium hexaboride, this anomalous behavior of S(T) is accompanied by the appearance of weak-carrier-localization-mode asymptotics in the conductivity (σ(T) ∝ T ^0.39), while the paramagnetic susceptibility χ(T) and the effective mass of charge carriers m _eff(T) vary according to a power law (χ(T), m _eff(T) ∝ T ^?0.8) in the temperature interval T = 10–80 K. This behavior corresponds to renormalization of the density of states at the Fermi level. The observed anomalous behavior of thermopower in CeB₆ and other cerium-based intermetallic compounds is attributed to the formation of heavy fermions (many-body states in the metal matrix) at low temperatures.     

The inertia of an S-shaped volt-ampere characteristic and the self-oscillation frequency limits in multilayered heterostructures

Radiophysics and Quantum Electronics -     

Comments on the nature of ballistic transport in small semiconductor devices at low applied voltage

A simple one-dimensional scattering model is proposed to calculate the apparent low field conductivity for small semiconductor devices in the near ballistic regime. Size dependence of the conductivity and voltage vs distance profiles in the sample are investigated.     

The thermodynamic parameters of phonon-soliton equilibrium in one-dimensional Frenkel-Kontorova systems

The temperature dependences of the internal energy of a canonical ensemble of Frenkel-Kontorova systems, which are one-dimensional chains of material points linked by elastic bonds in a periodic potential, were studied by the Monte Carlo method with importance sampling. Such a model is an example of a system in which local contraction-extension states that can move as sole waves, solitons, are possible. The calculation results are analyzed on the basis of the model of an equilibrium reaction between a chain phonon and soliton that occurs at the given temperature. The model was used to estimate the thermodynamic parameters of phonon-soliton equilibrium and obtain the dependences of the enthalpy of equilibrium “reaction” on the incommensurability parameter of the chain γ. The enthalpy of this process was found to be described by a linear dependence on γ^−1/2 with a high correlation degree (r ² = 0.994).     

Total cross sections for photoabsorption on light nuclei in the energy range 600–1500 MeV

Experimental data of the GRAAL Collaboration on the total cross sections for photoabsorption on deuterium and carbon targets at gamma-ray energies in the range between 600 and 1500 MeV are presented. The experiment was performed in a beam of photons obtained by the method of the Compton backscattering of laser photons at the electron storage ring of the European Synchrotron Radiation Facility (ESRF, Grenoble, France) by using a wide-aperture detector covering a solid angle close to 4π. The total photoabsorption cross sections were determined by two independent methods: by subtracting the emptytarget background and by summing partial cross sections for meson photoproduction. The total cross sections for photoabsorption on quasifree protons and neutrons are shown to agree both in magnitude and in shape within a 5% precision of the measurements. In contrast to data previously available in the literature, both cross sections show distinctly the F ₁₅(1680) resonance at a photon energy of about 1 GeV. Data obtained in the present experiment for the cross sections for photoabsorption on a free and a bound nucleon are compared. This comparison reveals a substantial role of two-nucleon correlations in estimating the nuclear-medium effect on meson photoproduction.     

A plasmastatic model of the galathea-belt magnetic trap

The mathematical apparatus of plasmastatics, which includes the MHD equilibrium equation and steady-state Maxwell equations, is reduced, in two-dimensional problems arising due to symmetry, to a single scalar second-order elliptic equation with a nonlinear right-hand side known as the Grad-Shafranov equation. In this paper, we numerically solve a series of boundary value problems for this equation that model equilibrium plasma configurations in the magnetic field of the belt-like galathea trap in a cylinder with two plasma embedded conductors. The mathematical model is outlined, the results of calculations of the magnetic field and plasma pressure in the cylinder depending on the parameters of the problem are presented, and the main integral characteristics of the trap are calculated. The existence and uniqueness of the solution is discussed; the limiting values of the maximal pressure at which there exists a solution of the equilibrium problem are found.     

Intra-Nuclear Cascade (INC) code for simulation of meson photoproduction in nuclei

η meson photoproduction in the ¹⁴N nucleus was studied using simulations done with INC (Intra-Nuclear Cascade) code. The probability for mesons and nucleons to escape the nucleus on different steps of the reaction was evaluated. These results predict the possibility of studying elastic and inelastic η meson interactions with intra-nuclear nucleons using the recoil proton as a tag for the case of slow η meson and fast recoil proton.     

The Application of Adhesive Technologies in the Assembly of Antivibration Boring Arbor

The design of an antivibration boring arbor that includes an adhesive joint and the technological process of its assembly are developed. It is shown that the use of an adhesive joint allows one to significantly reduce the labor intensity of the assembly process of such arbors and their cost price, as well as to decrease the vibrations of a tool.