Combined Technology Fabrication of Spin-Valve Magnetoresistive Elements and Micromagnets

We present the research results of the fabrication technology of magnetoresistive (MR) elements based on the multilayer spin-valve magnetoresistive (SVMR) Ta–FeNiCo–CoFe–Cu–CoFe–FeNiCo–FeMn–Та nanostructures and CoNi micromagnets for the construction of digital galvanic interchanges and the magnetic field sensors. The results of experimental studies of test elements based on multilayer SVMR nanostructures with an MR effect from 7 to 8% and films of magnetically hard materials with a coercive force of up to 95 Oe formed on a single silicon die are presented.     

Piston-type radiator in a soft screen in the pekeris waveguide

A model problem is considered for a radiator in the form of a circular disk with a given pressure jump at its surface. The radiator is inserted in a soft screen coinciding with the upper boundary of the Pekeris waveguide. A series expansion of the sound field in normal modes is obtained. A numerical analysis of the radiation impedance and its components that are responsible for the radiation into the waveguide and into the halfspace is carried out.     

Crystal lattice defects and Hall mobility of electrons in Si: Er/Si layers grown by sublimation molecular-beam epitaxy

The density of crystal lattice defects in Si: Er layers grown through sublimation molecular-beam epitaxy at temperatures ranging from 520 to 580°C is investigated by a metallographic method, and the Hall mobility of electrons in these layers is determined. It is found that the introduction of erbium at a concentration of up to ～5 × 10¹⁸ cm^?3 into silicon layers is not accompanied by an increase in the density of crystal lattice defects but leads to a considerable decrease in the electron mobility.     

Crystal Structure of Tetralead Hexanitrate Ethylenediaminetetraacetatoplumbate(II) Tetrahydrate Pb4(NO3)6[PbC10H12O8]μ4H2O

The crystals of tetralead hexanitrate ethylenediaminetetraacetatoplumbate(II) tetrahydrate Pb₄(NO₃)₆[PbC₁₀H₁₂O₈]4H₂O were synthesized and studied by X-ray diffraction (MoK radiation, 2388 reflections, R _F = 0.0376, R _W = 0.0348). The orthorhombic unit cell (space group Fdd2, a = 18.995(2), b = 40.649(4), c = 8.5178(8) , Z = 8) contains 16 complex cations [Pb₂(NO₃)₃]²⁺, 8 complex anions [Pb(Edta)]^2–, and 32 crystallization water molecules. The organic and inorganic fragments alternating along the y axis are united into a single frame by the bridging oxygen atoms and by hydrogen bonds. The (Edta)^4– ligand, forming one ethylenediamine metallocycle and four glycinate ones, is compressed in the axial direction and stretched in the equatorial direction. The coordination polyhedron of the Pb²⁺ cation bound with the ligand is a strongly distorted trigonal antiprism. The inorganic fragment is a close-packed double layer of Pb atoms linked with each other by NO₃ groups. Thus lead atoms perform a dual function in the structure, forming both complex anions and outer-spheric cations.     

Hydrogen Peroxide Electrosynthesis on Nonplatinum Materials

A combination of electrochemical and physicochemical methods is used to investigate electrocatalytic and corrosion properties of nonplatinum materials in a direct hydrogen peroxide electrosynthesis by the oxygen ionization. A modifying action of ozone and hydroquinone added in solution is established. Surface properties of the electrocatalysts are studied. Presumably, the electrosynthesis occurs via a mixed path, which includes direct oxygen electroreduction catalyzed by redox processes involving surface groups and chemical oxidation processes.     

DSC analysis of Cu–Zn–Sn shape memory alloy fabricated via electrodeposition route

Cu–Zn–Sn shape memory alloy strips with composition range of 13.70–46.30 mass% Sn were fabricated by electrodepositing Sn on a shim brass surface and then subsequently annealed at a constant temperature of 400 °C for 120 min under flowing nitrogen. Subjecting the Sn-plated strips to differential scanning calorimetry (DSC) analysis revealed that the austenitic start (A _s) temperature was essentially constant at 225 °C while the martensite start (M _s) temperature was consistently within the 221.5–222 °C interval. Austenite to martensite phase transformation showed two distinct peaks on the DSC thermogram which can be attributed to the non-homogeneity of the bulk Cu–Zn–Sn ternary alloy. The latent heats of cooling and heating were found to increase with the mass% Sn plated on the shim brass. Effect of annealing temperature was also investigated wherein strips with an essentially constant composition of 26 mass% Sn were annealed at a temperature range of 350–420 °C for 120 min under flowing nitrogen. Varying the annealing temperature has no significant effect on the transformation temperatures of the ternary alloy.     

Photoelectric properties of Pb1−x−y Sn x Ge y Te:In epitaxial films

Pb_1–x–y Sn _x Ge _y Te:In epitaxial films are examined in a wide temperature interval and at various background fluxes. These films have high sensitivity to infrared radiation in the spectral range <20m. The lifetime depends exponentially on temperature and varies from several seconds at T=10 K to 10^–2 s at T=20 K. The two-electron model of Jahn-Teller centers is proposed to explain the results. Multielement photoresistors based on these films are fabricated and D*=1.7×10¹³ cm Hz^1/2 W^–1 at T=25 K is achieved. Noise of the photoresistors is independent of background flux when it varies from 10¹² cm^–2 s^–1 to 10¹⁸ cm^–2 s^–1. As compared with Si:Ga and Ge:Hg photoresistors, the responsitivity is several orders larger at the operating temperature 25–30 K.     

Experimental evidence of time-delay-induced death in coupled limit-cycle oscillators

Experimental observations of time-delay-induced amplitude death in two coupled nonlinear electronic circuits that are individually capable of exhibiting limit-cycle oscillations are described. The existence of multiply connected death islands in the parameter space of coupling strength and time delay for coupled identical oscillators is established. The existence of such regions was predicted earlier on theoretical grounds [Phys. Rev. Lett. 80, 5109 (1998); Physica (Amsterdam) 129D, 15 (1999)]. The experiments also reveal the occurrence of multiple frequency states, frequency suppression of oscillations with increased time delay, and the onset of both in-phase and antiphase collective oscillations.     

X-Ray Photoelectron Spectroscopy of Stabilized Zirconia Films with Embedded Au Nanoparticles Formed under Irradiation with Gold Ions

Nanosized films of stabilized zirconia with Au nanoparticles formed by implanting Au ions are studied by X-ray photoelectron spectroscopy and transmission electron microscopy. The effect of irradiation of films with Au ions and postimplantation annealing on the distribution of chemical elements and zirconium- containing ZrO _x compounds over the depth of the films is studied. Based on the data on the dimensional shift of the Au 4 f photoelectron line, the average value of the nanoparticle size is determined.