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Tytuł:
Magnetic properties of hexagonal graphene nanomeshes
Autorzy:
Zwierzycki, M.
Ryndyk, D.
Powiązania:
https://bibliotekanauki.pl/articles/1054780.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.Pr
75.75.-c
72.25.Dc
Opis:
Graphene nanomeshes are the nanostructures consisting of graphene flake with a regular pattern of antidots (holes) punched through it. Thanks to the energy gaps opening in electronic spectrum, nanomesh-based transistors offer improved I_{on}/I_{off} ratio of the collector current while supporting up to 100 larger driving currents than nanoribbon-based devices. In this paper the electronic and magnetic structure of graphene nanomeshes with hexagonally shaped antidots was studied. It has been found that the internal zigzag edges support magnetic moments and that lowest energy magnetic configuration is antiferromagnetic. The density of states calculated for ground state configuration exhibit the energy gap which can be substantially reduced upon switching (e.g. by external magnetic field) to ferromagnetic configuration. Based on this we predict that the structure will exhibit magnetoresistive effect, which makes graphene nanomeshes of this kind relevant for spintronic applications.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 830-832
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoresistance of Si/Nb/Si Trilayers
Autorzy:
Zaytseva, I.
Cieplak, M.
Abal'oshev, A.
Dluzewski, P.
Grabecki, G.
Plesiewicz, W.
Zhu, L.
Chien, C.
Powiązania:
https://bibliotekanauki.pl/articles/1537220.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.62.-c
74.25.F-
74.25.Ha
74.62.En
Opis:
We study the superconductor-insulator transition in Si/Nb/Si trilayers, in which the thickness of Si is fixed at 10 nm, and the nominal thickness of Nb changes in the range between d = 20 nm down to d = 0.3 nm. The transmission electron microscopy indicates the formation of the mixed Nb-Si layer for small d. Both the thickness-induced, and the magnetic-field induced superconductor-insulator transition is observed. The crossing point of the isotherms at the critical field $B_{c}$ decreases with decreasing d, and it is T-independent at temperatures below 300 mK. At larger fields the weak peak in magnetoresistance appears in some of the films.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 406-408
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strain Relaxation in Thin Films of La$\text{}_{1.85}$Sr$\text{}_{0.15}$CuO$\text{}_{4}$ Grown by Pulsed Laser Deposition
Autorzy:
Zaytseva, I.
Cieplak, M. Z.
Abal'oshev, A.
Berkowski, M.
Domukhovski, V.
Paszkowicz, W.
Shalimov, A.
Powiązania:
https://bibliotekanauki.pl/articles/2047252.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.-a
74.62.-c
74.72.Dn
74.78.Bz
74.25.Fy
Opis:
X-ray diffraction, resistivity, and susceptibility measurements are used to examine the effects of film thickness d (from 17 to 250 nm) on the structural and superconducting properties of La$\text{}_{1.85}$Sr$\text{}_{0.15}$CuO$\text{}_{4}$ films grown by pulsed laser deposition on SrLaAlO$\text{}_{4}$ substrates. For each d the film sgrow with a variable strain, ranging from a large compressive strain in the thinnest films to a negligible or tensile strain in thick films. Our results indicate that the tensile strain is not caused by the off-stoichiometric layer at the substrate-film interface. Instead, it may be caused by the extreme oxygen deficiency in some of the films.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 185-188
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Transport Critical Current Densities of $MgB_2//Fe//Cu$ Multifilament Tapes without Any Intermediate Annealing
Autorzy:
Yucel, E.
Terzioglu, C.
Varilci, A.
Gencer, A.
Belenli, I.
Powiązania:
https://bibliotekanauki.pl/articles/1489874.pdf
Data publikacji:
2012-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Ad
84.71.Mn
74.62.-c
74.25.Sv
74.25.F-
Opis:
We have fabricated superconducting 6 and 7 filaments $MgB_2//Fe//Cu$ tapes by ex situ powder-in-tube method using Cu-sheath without any intermediate annealing. Properties of two different multicore $MgB_2//Fe//Cu$ tapes annealed at 900C for 2 h in high purity argon gas atmosphere were compared. The samples were characterized using scanning electron microscope, X-ray diffraction, electron dispersive spectroscopy, optical microscopy, critical transition temperature, transport critical current density, and magnetic measurements. Transport critical current densities of the 6 and 7 filaments tapes were found to be 450 A/cm^2 and 190 A/cm^2 at 20 K, respectively. From X-ray diffraction measurements, lattice parameters a and c were determined. From dc resistivity measurements, the connectivity between grains was investigated by using Rowell's connectivity analysis.
Źródło:
Acta Physica Polonica A; 2012, 121, 3; 660-665
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermoelectric Effect in the Normal Conductor-Superconductor Junction: A BTK Approach
Autorzy:
Wysokiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/1418323.pdf
Data publikacji:
2012-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.45.+c
74.25.fg
73.23.Ad
Opis:
The thermopower of the junction between normal conductor and s-wave superconductor has been investigated. For this purpose we have analyzed in detail a simple generalization of the Blonder-Tinkham-Klapwijk theory by taking into account explicitly an energy dependence of the density of states near the Fermi level. Both linear and nonlinear thermopowers have been calculated for 3D free electron gas, 3D Fermi liquid, and the case with Van Hove singularity in the vicinity of the Fermi level. In the linear regime, for all models, the thermopower as function of temperature has a clear maximum with its position and the value depending strongly on the junction barrier strength. In the nonlinear regime, we have found very large values of the thermopower (up to 8 $k_{B}$/e) and strongly asymmetric behavior with respect to the change of the temperature gradient sign.
Źródło:
Acta Physica Polonica A; 2012, 122, 4; 758-764
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Andreev Conductance through a Quantum Dot Strongly Coupled to Ferromagnetic and Superconducting Leads
Autorzy:
Wójcik, K.P.
Weymann, I.
Powiązania:
https://bibliotekanauki.pl/articles/1032390.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
72.15.Qm
74.45.+c
72.25.-b
Opis:
We analyze the Andreev conductance through a quantum dot strongly coupled to one ferromagnetic and one superconducting lead. The transmission due to the Andreev reflection is obtained from the numerical renormalization group method. We show that at low temperatures, depending on the dot level position, the Andreev conductance exhibits a peak at zero bias due to the Kondo effect, which can be split by the exchange field due to spin-dependent coupling to ferromagnetic lead.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 143-145
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tunneling Charge Transport in Graphene-Based Superconductor Junctions
Autorzy:
Wojciechowski, R.
Kowalewski, L.
Nogala, M.
Powiązania:
https://bibliotekanauki.pl/articles/1427098.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.45.+c
72.80.Vp
72.25.-b
Opis:
We study the spin polarized electron and hole tunneling transport through a graphene-based ferromagnet$(GF_1)$-insulator$(GI_1)$-superconductor$(G_{S})$-insulator$(GI_2)$-ferromagnet$(GF_2)$ junction. Proximity induced spin polarization and superconductivity in a graphene sheet are assumed to be created by superconducting and ferromagnetic electrodes placed on the top of the graphene. Using a four-dimensional version of the Dirac-Bogoliubov-de Gennes equation with appropriate boundary conditions we investigate the tunneling processes through the junctions. In particular, we present calculations of the amplitudes of normal and Andreev reflections as a function of the energy of the incident electron for a wide range of the model parameters, such as the strength and orientation of the exchange field, the barrier strength, and the distance between the two ferromagnetic layers. The tunneling transport processes in the graphene-based double junction GF/GI/$G_{S}$/GI/GF are compared with those in non-graphene-based junctions.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1092-1094
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
2D Angular Correlation of Annihilation Radiation: Current Trends and Future Possibilities
Autorzy:
West, R. N.
Powiązania:
https://bibliotekanauki.pl/articles/1933550.pdf
Data publikacji:
1995-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.28.+d
71.25.Ηc
78.70.Bj
Opis:
Recent improvements in two-dimensional angular correlation measurement and analysis techniques have greatly increased the power of the method to image the Fermi surfaces of electronically complex systems. That, and the further and dramatic improvement that must result when the present radioisotope positron sources are replaced by intense monoenergetic positron beams are discussed and illustrated.
Źródło:
Acta Physica Polonica A; 1995, 88, 1; 249-256
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Diagram and Activation Energy for Vortex Pinning in Nb/(Co,Pd) Superconductor-Ferromagnet Bilayer
Autorzy:
Syryanyy, Y.
Aleszkiewicz, M.
Cieplak, Marta
Zhu, L.
Chien, C.
Powiązania:
https://bibliotekanauki.pl/articles/1374109.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.F-
74.25.N-
74.25.Wx
74.62.-c
74.70.-b
74.78.-w
74.78.Fk
75.70.Kw
75.70.-i
Opis:
Using the magnetoresistance measurements we study the phase transition line and the activation energy for vortex pinning in superconductor/ferromagnet bilayer, built of a ferromagnetic Co/Pd multilayer with perpendicular magnetic anisotropy, and a niobium film, with insulating layer in-between to eliminate proximity effect. The domain width is reversibly pre-defined using the angle-dependent demagnetization. We find that the enhancement of the activation energy for vortex pinning by magnetic domains is rather modest, by a factor of about 2.1. We attribute this to large domain width, and large dispersion of the domain width in this bilayer.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-123-A-126
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxygen Deficient YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$: Two Superconducting Phases
Autorzy:
Stankowski, J.
Ślązak, A.
Kempiński, W.
Andrzejewski, B.
Reichel, B.
Plesch, G.
Powiązania:
https://bibliotekanauki.pl/articles/2037166.pdf
Data publikacji:
2004-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.62.Bf
74.62.-c
74.25.Nf
Opis:
A set of oxygen deficient powder and granular samples of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ ceramics was studied by means of thermogravimetric and magnetically modulated microwave absorption methods. Especially the last method has turned out to be a powerful method, which was used to determine the dependence of critical temperature T$\text{}_{c}$ on the oxygen parameterδ. Using these methods it has been shown that the removing of oxygen evokes the inhomogeneous oxygen distribution in the samples and a change in carrier concentration till to the loss of superconducting properties. A superconducting phase with T$\text{}_{c}$=60 K, which occurs in oxygen deficient YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ sample, is an unstable phase.
Źródło:
Acta Physica Polonica A; 2004, 105, 3; 287-294
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gamma Radiation Absorption Characteristics of Concrete with Components of Different Type Materials
Autorzy:
Stanković, S.
Ilić, R.
Janković, K.
Bojović, D.
Lončar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1537948.pdf
Data publikacji:
2010-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
28.41.Qb
29.25.Rm
29.27.Eg
29.85.-c
Opis:
Nuclear facilities as nuclear power stations, nuclear research reactors, particle accelerators and linear accelerator in medical institution using concrete in building construction. The different type materials of the aggregate as component of concrete were analyzed to provide radiation protection. The energy deposited the transmission factor and the mass attenuation coefficients in ordinary and barite concretes have been calculated with the photon transport Monte Carlo software. The numerical simulations results show that using barite as an aggregate in the concrete is one of the solutions for gamma ray shielding. Thereat, it is shown non-destructive method for determining the gamma radiation absorption characteristics of concrete.
Źródło:
Acta Physica Polonica A; 2010, 117, 5; 812-816
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical Kinetic Modelling and Representing Design Equation for a Packed Photoreactor with Immobilised TiO2-P25 Nanoparticles on Glass Beads in the Removal of C.I. Acid Orange 7
Autorzy:
Sheidaei, B.
Behnajady, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/185458.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heterogeneous photocatalysis
batch-recirculated photoreactor
design equation
mathematical kinetic modelling
TiO2-P25 nanoparticles
C.I. Acid Orange 7
fotoreaktor
modelowanie matematyczne
Nanocząstki TiO2-P25
CL kwas pomarańczowy 7
Opis:
In this work, a design equation was presented for a batch-recirculated photoreactor composed of a packed bed reactor (PBR) with immobilised TiO2-P25 nanoparticle thin films on glass beads, and a continuous-flow stirred tank (CFST). The photoreactor was studied in order to remove C.I. Acid Orange 7 (AO7), a monoazo anionic dye from textile industry, by means of UV/TiO2 process. The effect of different operational parameters such as the initial concentration of contaminant, the volume of solution in CFST, the volumetric flow rate of liquid, and the power of light source in the removal efficiency were examined. A rate equation for the removal of AO7 is obtained by mathematical kinetic modelling. The results of reaction kinetic analysis indicate the conformity of removal kinetics with Langmuir-Hinshelwood model (kL-H = 0.74 mg L-1 min-1, Kads = 0.081 mg-1 L). The represented design equation obtained from mathematical kinetic modelling can properly predict the removal rate constant of the contaminant under different operational conditions (R2 = 0.963). Thus the calculated and experimental results are in good agreement with each other.
Źródło:
Chemical and Process Engineering; 2015, 36, 2; 125-133
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Universal Critical Quantum Properties of Cuprate Superconductors
Autorzy:
Schneider, T.
Powiązania:
https://bibliotekanauki.pl/articles/1953179.pdf
Data publikacji:
1997-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.62.-c
74.72.-h
74.62.Dh
74.25.-q
Opis:
Using the scaling theory of quantum critical phenomena we explore the occurrence of universal critical behavior at the insulator-to-superconductor and superconductor-to-normal state transitions at zero temperature. Experimentally, these phase transitions are driven by doping and correspond to critical end points of the phase transition line in the temperature-hole concentration plane. Provided that the order parameter is a complex scalar in two dimensions, and that the London relation between superfluid number density and magnetic penetration depth holds, the scaling theory predicts universal behavior close to the insulator-to-superconductor transition. In particular, transition temperature and zero temperature penetration depth are universally related and the sheet resistance adopts a universal value. These predictions agree remarkably well with available experimental data and provide useful constraints for a microscopic theory.
Źródło:
Acta Physica Polonica A; 1997, 91, 1; 203-212
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Opto-Magnetic Method for Epstein - Barr Virus and Cytomegalovirus Detection in Blood Plasma Samples
Autorzy:
Papić-Obradović, M.
Kojić, D.
Matija, A.
Powiązania:
https://bibliotekanauki.pl/articles/1537895.pdf
Data publikacji:
2010-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.20.Kf
33.57.+c
42.25.Ja
42.30.-d
42.70.Jk
87.19.xd
Opis:
Motivated by characterization of paramagnetic materials (Al, Mn and Ti) and diamagnetic materials (Cu, C and Zn) by opto-magnetic method that is based on light-matter interaction using digital imaging, we present results of Epstein-Barr virus (EBV) and cytomegalovirus (CMV) detection in blood plasma. To investigate light-blood plasma interaction we use wavelength difference of diffuse white light and reflected polarized light in red and blue channels of digital images (opto-magnetic method). Digital images of samples are analyzed by spectral convolution algorithm for light-matter interaction analysis. Since opto-magnetic method can detect very small difference between normal and pathological tissue states it is advantageous in comparison with classical methods. Especially it is important for early detection of suspicious tissue states and detection of viral infection presence in plasma. We compared our results with results of standard biomedical test for EBV and CVM, as a reference, and found out for group of 40 samples significant correlation of 93. 6%.
Źródło:
Acta Physica Polonica A; 2010, 117, 5; 782-785
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Methods of forecasting VAT revenues for the state budget of Ukraine
Autorzy:
Okseniuk, Oksana
Powiązania:
https://bibliotekanauki.pl/articles/646256.pdf
Data publikacji:
2015-06
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
VAT
forecast
state budget
C53
E62
H25
Opis:
VAT is the main indirect tax in Ukraine, among other countries, providing one of the largest items of state budget revenues. The presence of the VAT refund procedure and the need to cover public spending with the revenues from VAT administration require that an effective method of planning and forecasting VAT revenues for the new fiscal year be used. The purpose of the article was to analyze the effectiveness of two methods of forecasting of VAT revenues, such as the moving average method and the method of correlation and regression. This was done by analysing the effectiveness of forecasts made for previous years and comparing them with actual data to make the forecast of VAT revenues using these methods for 2014–2016 years and identifying the main causes of problems in the forecasting process. The results show that the forecasts based on two methods (correlation and regression analysis and double moving average) are sufficiently accurate. After making certain adjustments, these methods can be used at the national level.
Źródło:
Ekonomia Międzynarodowa; 2015, 010
2082-4440
2300-6005
Pojawia się w:
Ekonomia Międzynarodowa
Dostawca treści:
Biblioteka Nauki
Artykuł

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