Solid State Phenomena Vols. 152-153

Abstract: In the present paper the dispersive equation for surface polaritons localized at the ferromagnet - high temperature superconductor interface structure have been obtained. The main characteristics dependences upon the external magnetic field are analyzed in the frame of the electromagnetic approach for transverse electric (TE) polarization wave. The analysis for different orientations of superconductor crystallographic axes relative to wave vector directions is carried out.

Abstract: In this work magnetoimpedance (MI) behaviour was studied experimentally for Fe19Ni81(175 nm)/Cu(350 nm)/Fe19Ni81(175 nm) sensitive elements deposited by rf-sputtering. A constant magnetic field was applied in plane of the sandwiches during deposition perpendicular to the Cu-lead in order to induce a magnetic anisotropy. Sandwiches with different width (w) of FeNi parts were obtained. The complex impedance was measured as a function of the external magnetic field for a frequency range of 1 MHz to 700 MHz for MI elements with different geometries. Some of MI experimental data are comparatively analysed with finite elements numerical calculations data. The obtained results can be useful for optimization of the design of miniaturized MI detectors.

Abstract: Y3Fe5O12 (YIG) films were pulsed laser deposited onto the Gd3Ga5O12(111) substrates. Processing conditions were optimized to obtain films with a narrow ferromagnetic resonance (FMR) linewidth: 0.9 Oe in 1.22 μm thick YIG at 9 GHz. Due to sharp film-to-substrate interface YIG films remain strained hence possess unusually high lattice mismatch induced uniaxial anisotropy Hu = - 880 Oe. We fabricated and tested magnetostatic surface wave (MSSW) band pass hybrid-type filters with YIG film lain on transducers alumina board. MSSW filter with antennas areal size of 2 mm2 at 7.5 GHz shows insertion loss – 9 dB and a resonant 3 dB bandwidth as narrow as 12.5 MHz.

Abstract: Thickness modes of magnetoelastic waves (MEW) guided by ferromagnetic film have been investigated. Propagation of two mutually perpendicular MEW one of which is parallel to a normal to the surface has been considered. It has been shown that resonant frequencies of standing MEW depend on the wave number of a wave propagating along a surface. Plots illustrating dependence of thickness shear modes upon wave vector kz of MEW traveling in a surface plane have been presented.

Abstract: It is known from experimental data that bulk metallic samples reflect microwaves while powdered samples can absorb such radiation and be heated efficiently. In the present paper we investigate theoretically the mechanisms of penetration of microwave radiation through a layer of metallic powder and microwave heating of such system.

Abstract: Microwave devices as circulators or tunable filters demand nowadays small size and broad bandwidth. Ferromagnetic nanowired membranes are ideal candidates for this purpose. This paper focuses on the dielectric properties of such substrates, as influenced by the ferromagnetic nature of nanowires and their filling factor. Two particular cases are considered: a membrane filled up to its top with nanowires, forming a one-layer substrate, and a membrane filled up to a certain percentage of its height with nanowires, forming a two-layer substrate. The models proposed in this paper for each case take the inductive and gyromagnetic effects in the wires into account. They predict for the one-layer case a magnetodielectric behavior which is tunable by applying an external magnetic field. The effect is no longer visible for the two-layer topology corresponding to microwave circuit applications.

Abstract: The mmW band photonic Tamm states in 1D magnetophotonic crystals are studied. It is shown the possibility to manipulate the eigenfrequencies of such states by an external magnetic field. Our experimental results are in a good agreement with theoretical prediction.

Abstract: This paper reports on the confined-chalcogenide phase change memory with thin metal interlayer (CCTMI) with the operating reset current of 0.6mA-30ns. This cell offers low reset current with simple architecture and fabrication. Thermal and heat flux distribution of both the normal-bottom-contact (NBC) and a proposed CCTMI PCM cells were carefully analyzed and simulated by two-dimensional finite element modeling. It is intriguingly found that the reset operation current of the CCTMI cell is 44% lower than that of the NBC. CCTMI has capability to solve an over-programming fail issue due to confined heat dissipation in active area.

Abstract: For the first time, the comparative investigations of structure and sorption efficiency of nano- and microsized magnetic-operated particles in respect to both the antigen and virus hepatitis B and also to the substance-markers (low-, middle- and highmolecular substances) were carried out. The sorption efficiency of magnetic particles: magnetite (Fe3O4), cobalt-ferrite (CoFe2O4), composite ferro-carbon (FeC) to the substances of different molecular weight was evaluated in vitro experiments. The high absorptive capacity to low- and highmolecular substance-markers has been observed for microsized composites of FeC. Absorptive capacity of the nanosized Fe3O4 and CoFe2O4 particles to the substance-markers was low. But the nanosized Fe3O4 and CoFe2O4 particles had a good absorptive capacity to virus of hepatitis B and its antigen (HBsAg). The sorption efficiency results of nano- and microsized magnetic particles correlate with the structure of their surface.

Abstract: The aim of the work is precise coupled –electromagnetic and temperature field analysis of an induction heating system by finite element method. Presented example is referred to real induction heating system. The problem was solved as nonlinear, transient and axisymmetrical. The numerical model of the coupled fields is based on the finite element method and electromagnetic and temperature distributions have been obtained using COMSOL 3.3 software package.