Modern Physics Letters B

The Ids–V_g characteristics of the aluminum-oxide glassy alloy (Ni_0.36Nb_0.24Zr_0.40)₉₀-H₁₀ field-effect transistor (GAFET) for gate–drain bias voltage from -50 to +50 μV were measured at room temperature. We observed four kinds of drain current oscillations for gate voltage at two-current plateau regions of -20~-15 and +35~+40 μV. The transistor showed the three-dimensional Coulomb diamond structure. From DC current standards I=ef, we get f=256 GHz for the first peak, being tunneling of one electron.

The influence of high pressure on the conductivity in the ab-plane of the oxygen deficient YBa₂Cu₃O_7-δ single crystals is investigated. It is determined that excess conductivity Δσ(T) in the YBa₂Cu₃O_7-δ single crystals in a wide temperature interval (T_c < T < T*, where T_c is the critical temperature and T* is the temperature that the PG regime begins) obeys an exponential temperature-dependence. The description of the excess conductivity with ) can be interpreted in terms of mean field theory. The temperature-dependence of the pseudo-gap is well described in the framework of the Bardeen–Cooper–Schrieffer (BCS) to the Bose–Einstein condensate (BEC) crossover theory. Increasing the applied pressure leads to the effect of narrowing the temperature range of implementation of the PG regime, thus extending the area of linear ρ(T) dependence in the ab-plane.

Within extensions of the new quantization rule approach in arbitrary dimensions, the Maslov indices and energy spectra of some exactly solvable potentials are presented. We find that the Maslov index for the harmonic oscillator in three dimensions agrees well with those obtained by other methods.

Based on the Langevin noise approach, a full quantum theory of radiation in laser plasma is explored, where the laser intensity is limited to the range of 10¹⁰ W/cm² to 10¹² W/cm² and the plasma is considered as a homogeneous dielectric background. By numerical calculation, the results show that the radiation is generated from the resonance of the plasma and the emitted rate of photons depends on the angular relation between the directions of radiation fields and the motion of the unbounded free electrons. In addition, the photons are more easily created under the lower collision frequency.

Using the spin-wave approximation elementary excitations of a semi-infinite two-dimensional S = ½ Heisenberg antiferromagnet are considered. The spectrum consists of bulk modes — standing spin waves and a quasi-one-dimensional mode of boundary spin waves. These latter excitations eject bulk modes from two boundary rows of sites, thereby dividing the antiferromagnet into two regions with different dominant excitations. As a result, absolute values of nearest-neighbor spin correlations on the edge exceed the bulk value.

The ground-state (GS) phase diagrams of spin-3/2 Ising model for ferromagnetic/antiferromagnetic (FM/AFM) interactions on a two-layer lattice are studied under a constant magnetic field by varying the crystal field values for general coordination number q in detail. Thus, it is found that the system exhibits twenty-nine topologically different GS configurations according to their GS phase diagrams obtained in the (J₂/J₁, J₃/qJ₁) planes. As the crystal field becomes more and more negative, the remaining phase configurations in the phase diagrams include only spin ±1/2 values as expected.

A model is developed to account for the size-dependent melting temperature of pure metallic and bimetallic nanowires, where the effects of the contributions of all surface atoms to the surface area, lattice and surface packing factors and the cross-sectional shape of the nanowires are considered. As the size decreases, the melting temperature functions of pure metallic and bimetallic nanowires decrease almost with the same size-dependent trend. Due to the inclusion of the above effects, the present model can also be applied to investigate the melting temperature depression rate of different low-dimensional system, accurately. The validity of the model is verified by the data of experiments and molecular dynamics simulations.

The spin Hamiltonian parameters (the anisotropic g factors and the hyperfine structure constants) and the local structure for the rhombic Cu²⁺ center in rutile (TiO₂) are theoretically investigated using the formulas of these parameters for a 3d⁹ ion in rhombically elongated octahedra. From the studies, the planar impurity-ligand bond angle is found to be about 5.8° larger than that for the host Ti⁴⁺ site due to the Jahn–Teller effect via bending the planar Cu²⁺–O^2- bonds, which yields much smaller rhombic distortion in the impurity center. The theoretical spin Hamiltonian parameters based on the above local angular distortion show good agreement with the experimental data, and the improvement of the calculation results are also achieved as compared with those of the previous works.

An electromagnetic cloak is a device which makes an object "invisible" for electromagnetic irradiation in a certain frequency range. Material parameters for the complementary medium-assisted external cylindrical cloak with N-sided regular polygonal cross-section are derived based on combining the concepts of complementary media and transformation optics. It can make the object with an arbitrary shape outside the cloaking domain invisible, as long as an "anti-object" is embedded in the complementary layer. The external cloaking effect has been verified by full-wave simulation.