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1
Content available remote

Metal-Polymer-Metal System in the High Static Electric Field

100%
Radny M., Karpowicz A.
Acta Physica Polonica A
|
1992
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vol. 81
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issue 2
325-331
EN
The negative differential resistance phenomenon evident on current-voltage (I-V) characteristics for Al-plasma-polymerized polystyrene-Al system is described by means of the Schottky-like barrier model constructed directly from the simplified electronic band structure of an insulator.
2
Content available remote

Microstructural Analysis and Transport Properties of RuO_2-Based Thick Film Resistors

80%
Gabáni S., Flachbart K., Pavlík V., Pietriková A., Gabániová M.
Acta Physica Polonica A
|
2008
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vol. 113
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issue 1
625-628
EN
RuO_2-based low temperature sensors appear as very good secondary thermometers, mainly in the temperature range below 4.2 K. This is due to their high temperature sensitivity and small magnetoresistance. Both properties are strongly influenced by the manufacturing process (mainly by firing temperature and firing time). In our contribution we show that the microstructure of sensors and the temperature dependence of their resistance R(T) down to 50 mK, in case when all sensors are prepared from the same paste, can be strongly influenced by change of the firing temperature from 800°C to 900°C. The paper also presents results on the X-ray microanalysis and the analysis of electrical conductivity of these sensors.
3
Content available remote

Tunneling Magnetoresistance in Ferromagnetic Junctions: Bias Dependence

80%
Barnaś J., Lee S., Holody P., Schelp L., Petroff F., Fert A.
Acta Physica Polonica A
|
1998
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vol. 93
|
issue 2
387-391
EN
Electron tunneling between two ferromagnetic electrodes across an insulating barrier is analysed theoretically and experimentally. The barrier is either uniform or it includes a layer of small magnetic metallic particles. Particular attention is paid to the origin of the tunneling magnetoresistance and its bias dependence, as well as to the effects due to Coulomb blockade.
4
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Thermoelectric Effects in Planar Tunnel Junctions

80%
Wilczyński M.
Acta Physica Polonica A
|
2012
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vol. 121
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issue 5-6
1188-1190
EN
The thermopower and the charge current generated by the finite temperature gradient applied to ferromagnetic planar tunnel junctions are investigated in the spin-polarized free-electron-like one-band model. It has been shown that the current depends almost linearly on the temperature difference between the electrodes while the thermopower does not depend significantly on the temperature gradient. The studied quantities depend on the magnetic configuration of the junction. The form of this dependence is sensitive to the height of the barrier, but is not sensitive to the temperature difference between the electrodes.
5
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Strong Reduction of 1/f Noise by Carbon Doping in Epitaxial Fe/MgO(100) 12~ML/Fe Magnetic Tunnel Junctions with Barrier Defects

80%
Herranz D., Guerrero R., Cascales J., Aliev F., Hehn M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
981-984
EN
We report on the strong influence of carbon doping on 1/f noise in fully epitaxial Fe/MgO(100) 12 ML/Fe magnetic tunnel junctions in comparison with undoped junctions with a large density of barrier defects. Carbon influences the relaxation of defects, the reconstruction of the interface and the symmetry transformation of interface resonance states, which are suggested to contribute to the strong reduction of the 1/f noise. Our study demonstrates that doping with light elements could be a versatile tool to improve the electron transport and noise in epitaxial magnetic tunnel junctions with a large density of barrier defects.
6
Content available remote

Investigation of Local Trapping States in Organic Molecular Crystals by Method of Thermally Modulated Space-Charge Limited Current

70%
Muzikante I., Silinsh Ε. A.
Acta Physica Polonica A
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1995
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vol. 88
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issue 2
389-399
EN
The method of thermally modulated space-charge limited current has been used for studying local charge carrier trapping state energy spectra in vacuum evaporated thin films and Langmuir-Blodgett multilayers of different organic molecular crystals. In case of evaporated thin polycrystalline layers of pentacene four sets of local trapping states in energy range from E_{t} = 0.35 to 0.06 eV were observed. In evaporated thin layers of dimethylaminobenzylidene indandione-1,3 five sets of trapping states from Ε_{t} = 0.59 to 0.28 eV were detected. In the evaporated layers of indandione-1,3 pyridinium betaine only a single set of very shallow trapping states close to the conductivity level was observed. In the Langmuir-Blodgett multilayers of vanadyl phthalocyanine and indandione-1,3 pyridinium betaine the activation energy E_{a} dependence on applied voltage U, E_{a}(U), for bulk conductivity is not step-like as in case of evaporated layers, but of rather complicated, oscillatory shape. Such character of the E_{a}(U) dependence may be explained by the specific quantum well structure of the Langmuir-Biodgett multilayers and spatially nonuniform trap distribution. However, for in-plane conductivity of indandione-1,3 pyridinium betaine films the E_{a}(U) dependence is step-like and two sets of trapping states at E_{t} = 0.45 ± 0.03 eV and E_{t} = 0.18 ± 0.03 eV were obtained. In case of bulk conductivity of the Langmuir-Blodgett layers the activation energy E_{a} at sufficiently high electric fields drops down to zero and the charge carrier transport switches to a "trap-free" regime.
7
Content available remote

Fowler-nordheim tunnelling in Au−TiO2−Ag film structures

61%
Aarik J., Bichevin V., Jõgi I., Käämbre H., Laan M., Sammelselg V.
Open Physics
|
2004
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vol. 2
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issue 1
147-159
EN
I-V-characteristics have been measured for Au−TiO2−Ag structures with TiO2 layers of 30 and 180 nm thickness. The TiO2 films were grown by atomic layer deposition (ALD) technique. In the case of negative bias on the Au electrode, the conduction currents through TiO2 layers follow the Fowler-Nordheim formula for field emission over several orders of magnitude. The bulk of the currents may be attributed to tunnelling, seemingly through a Schottky barrier at the Au−TiO2 junction. In the case of reversed polarity the currents are also observed, but cannot be interpreted as tunnelling.
8
Content available remote

Effect of Matrix onto Oxidation of Metallic Nanoparticles in Metal-Insulator Nanocomposite Films

61%
Fedotova J.
Acta Physica Polonica A
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2014
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vol. 125
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issue 6
1418-1420
EN
Paper reports the results of X-ray diffraction, X-ray absorption spectroscopy and the Mössbauer spectroscopy of metal-insulator films sintered in Ar+O atmosphere evidencing the difference in oxidation of FeCoZr nanoparticles embedded into Al_2O_3 and Pb(ZrTi)O_3 matrixes. It is proved that Al_2O_3 matrix with high resistance to oxidation favors the formation of nanoparticles with "metal core-oxide shell" structure, while fully oxidized nanoparticles are observed inside Pb(ZrTi)O_3 matrix.
9
Content available remote

Tailored Magnetic and Electric States in 3d-Metal-Insulator Films: Characterization and Applications

61%
Fedotova J.
Acta Physica Polonica A
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2014
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vol. 125
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issue 4
944-952
EN
Progress in designing of new low-cost magnetoelectronic planar devices requires new artificial films combining tuneable magnetic and electric properties. In this context, metal-insulator films are prospective for synthesis of materials with tailored physical properties that could be controlled with films composition and synthesis regimes. Present overview covers the summary of recent experimental results on complimentary and systematic study of macroscopic and local magnetic properties of films using vibrating sample magnetometer and Mössbauer spectroscopy with respect to phase composition and structural analysis at nanoscale by X-ray absorption spectroscopy in the extended X-ray absorption fine structure range, transmission electron microscopy and high-resolution transmission electron microscopy. Specific relationship between films structure and resulting magnetic properties (SP relaxation, core-shell exchange interaction, perpendicular magnetic anisotropy) is considered. Effects of magnetic and electric percolation in films are discussed in correlation with synthesis regimes (atmosphere of deposition, temperature of the substrate) and films composition. Physical mechanisms and models describing magnetic and electric properties of composite films are analyzed. Finally, technological approaches are proposed for tuning films properties towards their desired combination with respect to application in designing of sensors and planar (non-coil) inductive elements.
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