Solid State Phenomena Vols. 233-234

Abstract: Superconducting Nb/Au/Ca_1-xSr_xCuO₂/YBa₂Cu₃O₇ mesa-heterostructures were investigated. Dependencies of electrical parameters versus inverse capacitance were measured. A band diagram which takes into account an accumulation of holes in Ca_1-xSr_xCuO₂ interlayer and band bending due to difference of work functions was proposed. The dependencies of electrical parameters were analyzed by examining the quasipartical and superconducting currents.

Abstract: We report on microwave measurements of hybrid superconductor-ferromagnet-superconductor (SFF’S’) junctions with a composite oxide ferromagnetic bilayer with non-collinear magnetizations. Current-phase relation (CPR) of the junction superconducting current has been evaluated as a function of magnetic field. A significant part of the 2^nd harmonic in CPR, about 50%, was measured.

Abstract: Effect of the magnetic prehistory on the temperature dependence of the heat capacity of the superconducting Pb, La, Sn. has been studied. As soon as the external magnetic field riches the value H_ext = H_C the superconductivity is completely destroyed. The trapped flux was produced in the ring specimen after the magnetic field was turned off at T < T_C. We observed a difference of the value of the heat capacity between zero field cooled (ZFC) and field cooled (FC) states in zero magnetic field for the ring specimen. It is found that the FC heat capacity is smaller than the heat capacity both in the normal and in superconducting states.

Abstract: We study the superconducting transition temperature T_c of F2/F1/S trilayers (Fi is a metallic ferromagnet, S is a s-superconductor), where the long-range triplet superconducting component is generated at canted magnetizations of the F layers. In this paper we show that it is possible to realize different spin-valve effect modes - the standard switching effect, the triplet spin-valve effect, reentrant T_c(α) dependence or reentrant T_c(α) dependence with the inverse switching effect - by variation of the F2/F1 interface transparency or the exchange splitting energy. In addition, we show that positionof the T_c minimum can be changed by joint variation of the F2/F1 interface transparency and the layerthicknesses.

Abstract: Microwave absorption histeresis is measured in superconducting composites, prepared from MgB₂ , carbon nanotubes, graphene particles and iron nanoparticles. Iron nanoparticles were synthesized with using of isopropanol in the supercritical fluid state. Measurements showed that the greatest increase in the pinning force is observed in the “MgB₂ – (CNT-α-Fe)” composite.

Abstract: As a result of consecutive intravenous injections of combination from 0.05 up to 1.0 ml 1.0-10 % sol Dextran-ferrite (DF), and 0.001-0.02 ml Magnevist contrast-enhansend (CE) MRI, have reduced to 4 days time of early visualization CE MRI of proliferation centres of glial tumor. Electron-touch mapping DF in a tumor and a liver have defined size of a ratio of contents DF in a tumor to contents DF in a liver ≥ 100 at which combined photodynamic magneto-thermochemotherapy, was preferable and have increased life span of rats with glioma C6 (GC6) up to 166% and at glioblastoma 101/8 (GB 101/8) up to 74%.

Abstract: In this report, were studied the heating capability of magnetic nanoparticles (MNps) made from Zn-substituted manganese ferrite compounds Zn_xMn_1-xFe₂O₄ with Zn content varying from 0% to 90%. The MNps of diameter 5-25 nm were synthesized by co-precipitation of metal salt solution with NaOH solution. It was shown, that specific absorption rate (SAR) for the compound with Zn content of 20% is bigger than the other ones exhibited 1.5 W/g. Also SAR for the magnetic liquids made of the MNps shows bigger SAR values, which indicates the Brown relaxation mechanism in the system.

Abstract: Mössbauer studies of bioreduction products stabilized by acetone and ethanol were carried out at wide temperature range from 80 K to room temperature and in external magnetic field applied perpendicular to γ-beam at room temperature. The initial products (mixture of non-stoichiometric magnetite and maghemite) were formed during the iron reduction of synthesized ferrihydrite by bacterium G. ferrihydriticus. The addition of acetone and ethanol led to slight particle size decrease. The average size and magnetic moments were 11.2 nm and 524 µ_B, respectively.

Abstract: In this paper, we present results of theoretical modeling of the rise of temperature for the unit of time in a dilute suspension of the fiber ferromagnetic particles under the action of the linearly polarized oscillating magnetic field. Two mechanisms of the heat production, namely the particle rotation in the liquid and its internal remagnetization are considered. We study effect of the particle shape, its magnetic properties and rheological properties of the carrier liquid on the rise of temperature for the unit of time by the particles.