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.     

Iridium–Titanium Textured Electrodes: Production and Investigation by Electrochemical Scanning Tunneling Microscopy and Spectroscopy

A technique for the production of perfect thin-layered Ir coatings on inert Ti supports is developed. The highly textured coatings have some potential uses. Local topography and energy nonuniformness of the surface of such Ir electrodes are studied by electrochemical scanning tunneling microscopy (ESTM) and scanning tunneling spectroscopy (STS). In situ STM images of Ir–Ti textured electrodes with axial texture (111) are obtained with an atomic resolution at potentials of 0.3 to 1.2 V, in 0.05 M H₂SO₄ as well. Energy states of surfaces of Ir–Ti textured electrodes are studied with an atomic resolution using in situ STS by distance and voltage. Dependences of the tunneling current on the tunneling voltage and the tunneling-gap width are measured at Ir-surface potentials of 0.3 to 1.2 V. Effective potential barrier for the electron tunneling is estimated at different potentials of Ir.     

Kinetics of Mixed Crystal K2(SO4, CrO4) Growth from Aqueous Solution

The investigation of crystal growth kinetics and phase equilibria in the system K₂SO₄–K₂CrO₄–H₂O was carried out using the method for the determination of the saturation temperature and the growth rate by microscopic observation of the seed crystal behaviour. The kinetics of mixed crystal growth can be characterized by the expression V = 450.24σ^1,6,2, where σ is the value of effective supersaturation of the solution calculated by taking into account the specific features of the phase equilibria diagram. Use of this criterion allows the control of the rate of delta crystal growth from solutions of variable composition.     

Planar thiol-sensitive sensor elements for the determination of butyrylcholinesterase activity and analysis of its inhibitors

A method for the analysis of the thiocholine concentration, as well as the activity of the butyrylcholinesterase (BChE) enzyme and its inhibitors, using thiol-sensitive planar sensors has been proposed. Thiocholine sensitivity of the sensors was achieved by a mediator layer of manganese dioxide formed on a working carbon electrode. The detection limits for BChE and its inhibitor diazinon were 1 × 10^?10 M and 1 × 10^?9 M, respectively. The approach that was developed simplifies the analysis of inhibitors. It could be used for water quality and environmental monitoring.     

Generalization of the Boltzmann distribution for a nonideal gas

Using the concept of forbidden and accessible volumes to find the center of an individual particle in some volume, it is shown that the Boltzmann distribution is disrupted close to a shell bounding a nonideal gas. For an inhomogeneous weakly nonideal gas, an expression generalizing the Boltzmann distribution is obtained, including a dependence on parameters characterizing the particle interaction. It may be of interest to generalize this distribution to a system of Coulomb particles in order to consider the enriched and inversional layers arising in semiconductor structures. Institute of Physics and Engineering Research, N. I. Lobachevskii Nizhegorodsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 94–97, May, 1996.