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The Co2MnSi (CMS) Heusler alloy compound with ordered crystalline structure is attractive for a number of applications due to soft ferromagnetic properties, high Curie temperature (TC ≅ 985 K), high saturation magnetization (Ms ≅ 5.1 µB/f.u), and predicted full spin polarization of carriers. In this work, we report preparation and properties of nanocrystalline CMS films with thickness d = 120 nm magnetron sputtered onto Si(100) substrates followed by annealing in vacuum at Ta = 300 ÷ 500 °C. Nanocrystalline structure of partially ordered cubic B2 phase with grain diameter d = 15 ÷ 30 nm increasing gradually with Ta has been indicated after annealing at Ta ≥ 400 °C. The angle-dependent differential susceptibility measurements revealed an interesting evolution of magnetic properties of the films in a course of postdeposition annealing at Ta=500 °C. Formation of isolated FM particles demonstrating the angle-dependent coercivity Hc(α) following the well-known Stoner–Wohlfarth model has been indicated after 0.5 h annealing. However, the Kondorsky low Hc ~ 1/cosα demonstrating a strong pinning of domain walls has been certified for similar films after 1.5 h annealing. At the same time, long-term (~ 5 h) annealing at 500 °C revealed reduced magnetization of the films due to a decomposition of the material. Nevertheless, electrical transport measurements revealed low field magnetoresistance of these films of about 0.1% and 0.05% at 80 and 295 K, respectively, demonstrating tunneling of spin-polarized carriers between nanocrystalline grains. [ABSTRACT FROM AUTHOR]

Copyright of Lithuanian Journal of Physics is the property of Lithuanian Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lithuanian Journal of Physics is the property of Lithuanian Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lithuanian Journal of Physics is the property of Lithuanian Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lithuanian Journal of Physics is the property of Lithuanian Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nondoped BiFeO (BFO) and doped BiLaFeMnO (BLFMO) thin films ( d = 200-350 nm) were grown at 650-750 °C by RF sputtering on Si and SrTiO(100), coated by conductive LaNiO films and LaCaMnO/SrRuO bilayers. The complex dielectric permittivity of the films was measured at room temperature in the frequency range from 10 MHz to 10 GHz using parallel plate capacitor structures. Dielectric properties of the polycrystalline BFO films were compared with those of the epitaxial quality BLFMO films, and it was seen that the latter has better microwave performance than the former. The dielectric losses were below 0.05 at 1 GHz frequency, which may be acceptable for microwave applications. [ABSTRACT FROM AUTHOR]

We report on the synthesis of two naphthalene diimide-based organic derivatives: POANT containing electronically isolated 1,4,5,8-naphthalenetetracarboxylic diimide units and FCAND - a low-molar-mass compound with two different (fluorenone and 1,4,5,8-naphthalenetetracarboxylic diimide) electron-accepting units. Initial decomposition temperatures of 305°C and 390°C were indicated for FCAND and POANT, respectively. Organic semiconductor/Si heterostructures have been prepared by using spin coating (POANT, PEPK) and thermal evaporation in vacuum (FCAND). All heterojunctions demonstrated nonlinear I-U dependences and defined rectifying properties. The Schottky thermoionic emission model has been applied to explain the carrier transport and to estimate the barrier height and the ideality factor n of heterojunctions. [ABSTRACT FROM AUTHOR]

The corrosion of Au–Pd–In alloy, which is of great importance in dentistry, has been studied using an electrochemical quartz crystal microbalance (EQCM) in simulated physiological solutions. The alloy was deposited on quartz substrates by means of magnetron sputtering (MS). Analysis performed using X-ray photoelectron spectroscopy showed that the chemical composition of the sputtered deposit was similar to that of the MS target made of conventional casting alloy. Investigations by X-ray diffraction indicated a crystalline structure of the MS alloy. The electrochemical and corrosion behaviour of the Au–Pd–In alloy was studied in three simulated physiological solutions: 0.9 M NaCl, 0.1 M NaCl + 0.1 M lactic acid and artificial saliva. Determination of break down potential was complicated by the anodic gold dissolution due to formation of a chloride complex. The onset of anodic currents, therefore, indicated not the potential at which the passive layer starts to be destroyed, but the exceeding of the Au/AuCl4 − equilibrium potential, which does not directly reflect corrosion resistance. The EQCM measurements under open circuit conditions indicated corrosion as an increase in mass, caused by the accumulation of corrosion products on the alloy surface. The increase in mass in acidic solution (pH 2.2) was similar to that in neutral solution (pH 6.5), which implies dissolution of corrosion products to be insignificant. [ABSTRACT FROM AUTHOR]

Thin films of La0.67 Ca0.33 MnO3+δ (d ≈ 200 nm) grown at 750° C on MgO(100) substrates by pulsed laser deposition were annealed in various oxygen atmospheres. The LaF3 , CaF2 and Mn overlayers (d ≈ 5-10 nm) have been evaporated onto the films in order to saturate the compound by La, Ca or Mn during subsequent annealing at 900° C in air. Further, the pulsed injection CVD method has been utilized to prepare series of La1−x Srx MnO3 films with x = 0÷0.5 on LaAlO3 (100). The effect of composition variations on electrical resistivity and magnetoresistance of the films as well as on their optical transmission and reflection spectra in the energy range between 0.2 and 4.0 eV has been investigated. [ABSTRACT FROM AUTHOR]

The resistance relaxation after switch-off of high magnetic field pulses of 20-40 T was studied for two series of La0.67 Ca0.33 MnO3 thin films. The response dynamics was obtained for temperature range 77-300 K. It is shown that the relaxation time is sensitive to the temperature of the resistivity maximum and to magnetoresistive properties of a film. The observed relaxation times are assumed to be related to existence of magnetic domains or intergrain material. [ABSTRACT FROM AUTHOR]

The dynamics of light induced switching from the super-conducting or mixed state to the normal state were investigated in thin Y-Ba-Cu-0 films biased by high-current nanosecond pulses. It was demonstrated that the subnanosecond duration voltage transients with amplitudes of up to several hundred volts which are generated by the light triggered super-conducting opening switch are the result of film heating by light pulses and the bias current. [ABSTRACT FROM AUTHOR]

We report fabrication and electrical characterization of the organic-inorganic semiconductor diode structures formed by evaporating thin films of three novel low molecular mass organic compounds on n-type Si substrates. The organic compounds containing carbazole and triphenylamine structural units, namely: 9,9′-bis(4-butylphenyl)-3,3′- -bicarbazolyl (BPBC), 4-(1H-perimidin-2-yl)-N,N-diphenylbenzenamine (PER) and 9,9′-diethyl-3,3′-bicarbazolyl (EBC) have been synthesized. The current-voltage characteristics of the Au/(BPBC, EBC, PER)/n-Si diode structures measured at T = 295 K revealed rectifying behavior with a potential barrier height values of 0.71 eV, 0.73 eV, 0.76 eV, respectively. [ABSTRACT FROM AUTHOR]

The magnetoresistive and electroresistive properties of thin nonhomogeneous La0.67Ca0.33MnO3 films have been investigated after thermocycling from 200 to 80 K. Highly resistive states with an additional low temperature resistance peak near 95 K were revealed in the films using probe currents as low as 1 μA. The film resistance at the peak is sensitive to the probe current strength and the applied magnetic field. The highly resistive state is metastable and is associated with the formation of martensitic inclusions during the thermocycling. The exhibition of memory effects during the cooling also suggests the idea of the presence of martensitic-type transformations. [ABSTRACT FROM AUTHOR]