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1
Content available remote Electric properties of composite ZnO-based ceramics doped with Fe
Fedotov A. S., Pashkevich A. V., Bliznyuk L. A., Kasiuk J., Fedotov A. K., Basov N. A., Svito I. A., Budzyński M., Wierteł M., Żukowski P.
Przegląd Elektrotechniczny
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2018
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R. 94, nr 3
197--199
EN
This work is focused on the analysis of phase structure and temperature dependences of electric resistivity ρ(Т) in ZnO-based composite ceramics (ZnO)90(FexOy)10, doped with Fe by the addition of 10 wt.% of one of the iron oxides FexOy.
PL
Praca koncentruje się na analizie struktury fazowej oraz zależności temperaturowych rezystywności elektrycznej ρ(Т) kompozytów ceramicznych (ZnO)90(FexOy)10 opartych o ZnO, domieszkowanych Fe poprzez dodanie 10% wag. jednego z tlenków żelaza FexOy.
2
Content available remote Influence of ion irradiation on temperature dependent electrical transport behavior of thin graphite flakes
Khamaj J. A.
Materials Science Poland
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2016
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Vol. 34, No. 2
399--403
EN
In this article, the influence of ion irradiation on temperature dependent electrical transport characteristics of thin graphite flakes was investigated. Thin graphite flakes were exfoliated by mechanical exfoliation method. Scanning electron microscopy was used to study surface morphology of the graphite flakes. The resistance versus temperature studies revealed that the graphite flake not subjected to Ga+ ion-irradiation showed a perfect metallic behavior, while the graphite flake after ion-irradiation showed a semiconducting behavior. The current-voltage (I-V) characteristics of bare and ion-irradiated graphite flakes were investigated. The bare graphite flake showed an ohmic-type I-V characteristics representing metallic behavior, while the ion-irradiated graphite flake showed a non-linear type diode-like characteristics. The temperature-dependent conductance measurements of ion-irradiated graphite flake were also performed and discussed in detail. The effect of Ga+ ions on the electronic transport behavior of thin graphite flakes has been discussed based on the investigation results.
3
Content available remote Influence of the columnar structure of heteroepitaxial nitride layers on the transport of electrons
Szyszka A., Paszkiewicz B., Paszkiewicz R., Tłaczała M.
Materials Science Poland
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2008
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Vol. 26, No. 1
221--227
EN
The influence of the columnar structure of heteroepitaxial nitride layers on electronic transport has been described within the model of thermionic emission of carriers through potential barriers formed at grain boundaries. Dependence of the potential barrier height on the material properties and applied external voltage has been calculated. Potential barriers heights for gallium nitride layers grown by the metalorganic vapour phase epitaxy method has been estimated to be in the range of 20-60 meV and 10-40 meV in the dark and under illumination, respectively.
4
Content available remote Prospect for research on spintronics of U3As4 ferromagnet and its semiconducting Th derivatives
Wiśniewski P., Henkie Z.
Materials Science Poland
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2007
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Vol. 25, No. 2
533--539
EN
Low magnetic field magnetisation along easy magnetic axis [111], Hall resistivity and the effect of magnetic field of different directions on U3As4 resistivity along the easy axis as well as along the hard one ([100]) have been examined. The Hall resistivity reaches the highest value ?H = 1.75 uqm at T = 113 K where it yields the giant anomalous Hall coefficient RS = 6.25 uqm T-1 and the tangent of the Hall angle of 0.42. Magnetic field exceeding the demagnetisation field Hdemag < 0.28 T changes the resistivity by up to 36 % at T = 77 K.
5
Content available remote Electronic transport through carbon nanotubes with ferromagnetic electrodes or in magnetic fields
Krompiewski S.
Materials Science Poland
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2006
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Vol. 24, No. 3
649--657
EN
I study spin-dependent electronic transport through carbon nanotubes (CNTs) either sandwiched between ferromagnetic contacts or placed at external magnetic fields. The attention is directed to the conductance dependence on: (i) geometrical sizes (length and diameter of the CNTs), (ii) chirality, and (iii) conditions at CNT/contact interfaces. The CNTs are end-contacted to fcc (111) metallic leads, and relative atomic positions at the interfaces are determined by a relaxation procedure. Additionally a charge neutrality condition is imposed on the extended molecule (i.e. the CNT with a few atomic layers of the leads) in order to fix the band lineup of the whole system. Using a single-band tight-binding model and a Green's function technique it is shown that if electrodes are ferromagnetic - a quite considerable giant magnetoresistance effect can occur. For paramagnetic electrodes in turn, in the parallel magnetic field, clear Aharonov-Bohm oscillations are observed with distinct minima in the conductance. A depth of the dips depends on diameters of the CNTs, most likely due to some unintentional doping coming from the contacts. In the case of the perpendicular geometry, pronounced conductance oscillations appear whenever a magnetic length gets smaller than a perimeter of the CNT.
6
Content available remote Magnetic field sensors based on undoped In0.53Ga0.47As/InP heterostructures fabricated by molecular beam epitaxy and metalorganic chemical vapor deposition
Przesławski T., Wolkenberg A., Kaniewski J., Regiński K., Jasik A.
Optica Applicata
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2005
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Vol. 35, nr 3
627-634
EN
In this paper we, describe the design and fabrication process of Hall and magnetoresistor cross-shaped sensors using In0.53Ga0.47As/InP layer structures as active media. The influence of geometric correction factor GH on sensitivity parameters of these devices has been investigated. The results have been used in order to optimize the structure design behavior at temperatures ranging from 3 to 300 K. The large changes of the galvanomagnetic parameters vs. magnetic field and temperature allow these devices to be used as signal and measurement magnetic field sensors.
7
Content available remote Spin-dependent transport through a double dot system
Lipiński S., Bułka B. R., Krychowski D.
Materials Science Poland
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2004
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Vol. 22, No. 4
513--522
EN
The coherent transport through a set of two capacitively coupled quantum dots placed in a magnetic field and coupled to ferromagnetic electrodes is considered in the limit of infinite intra- and interdot interactions. The densities of states are calculated in an approximation that favours separate fluctuations of spin, orbital isospin, and simultaneous fluctuations of both of them. Apart from the Kondo peak, satellite many-body peaks are also found in the densities of states. Their positions and weights depend on the magnetic field and polarization of electrodes. This is reflected in the spin dependence of conductance remarkably varying for the voltage bias corresponding to the peak positions.
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