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Wyszukujesz frazę "74.25.F" wg kryterium: Temat


Tytuł:
Trapped field of YBCO bulk superconductors prepared by infiltration growth process
Autorzy:
Vojtkova, L.
Diko, P.
Piovarči, S.
Powiązania:
https://bibliotekanauki.pl/articles/1054776.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.81.Bd
61.50.-f
74.25.Ha
81.10.Fq
Opis:
Single grain Y₁Ba₂Cu₃O_{7-x} (YBCO) bulk superconductors were prepared from different starting precursors. In the first case, Y₂Ba₁Cu₁O₅ (Y211) powder as the solid phase and the liquid phase of mixture of YBa₂Cu₃O_{7-x}+BaCuO₂+CuO powders were used. In the second case, the solid phase was prepared from the mixture of Y₂O₃+BaCuO₂ instead of the conventionally used Y211, and as the liquid phase a mixture of Y₂O₃+BaCuO₂+CuO powders was used. The trapped field measurements at 77 K were performed and microstructure of samples was studied by polarized light microscopy. The positive influence of Y₂O₃+BaCuO₂ starting precursor on the oxygenation, Y211 particle refinement and measured trapped field is shown.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1048-1050
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermoelectric Effect in Photon-Assisted, Spin-Polarized Tunnelling through a Quantum Dot
Autorzy:
Bocian, K.
Rudziński, W.
Powiązania:
https://bibliotekanauki.pl/articles/1386730.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.Mk
73.23.Hk
73.63.Kv
74.25.F-
Opis:
Features of electric and thermal conductance, Seebeck coefficient as well as figure of merit in tunnelling through a single level quantum dot connected to external ferromagnetic leads are investigated theoretically using the equation of motion method within the nonequilibrium Green function technique. The influence of the harmonic ac field on the transport characteristics for the considered system is discussed in detail. In particular, it is shown that the photonic field strongly modulates the Seebeck coefficient, thus resulting in multi-peak structure of figure of merit. Thermoelectric phenomenon in a hybrid junction with the dot attached to two ferromagnetic and one superconducting lead is also discussed.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 484-486
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Superconducting and Magnetic States in $RuSr_2GdCu_2O_8$, Based on the Magnetic, Transport and Magneto-Caloric Characteristics
Autorzy:
Klamut, P.
Plackowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/1536600.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
75.30.-m
74.62.Bf
74.25.F-
75.30.Sg
Opis:
The article discusses selected properties of the non- and superconducting polycrystalline samples of $RuSr_2GdCu_2O_8$ and comments on the consequences of introducing insignificant sub-stoichiometry of Ru into the nominal formula. The magneto-resistive and the magnetic characteristics are interpreted in favour of the formation of intrinsically inhomogeneous superconducting phase, which seems stabilized along with the structural modifications enhanced with the modification of starting stoichiometry. The specific heat data reveals the small shift of the temperature of magnetic ordering $T_{m}$, which may suggest dilution of the magnetic sublattice of the Ru moments. The measurements of the magnetic field dependences of the isothermal magnetocaloric coefficient $M_{T}$ reveal no gain in the system magnetic entropy in a broad range of accessed fields and temperature. Whereas the multi-component character of the compound's magnetsm precludes from concluding on the magnetic ground state, the maximum in $M_T (H)$, which occurs at comparably weak magnetic field for temperatures in a vicinity of $T_{m}$ may reflect dominance of the ferromagnetic type interactions with a constrained correlation range. The literature explored models for the Ru magnetic ordering and also possible phase separation are brought into the discussion.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 254-260
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Pressure Effects on Electronic Structure of Iron Chalcogenide Superconductors $FeSe_{1-x}Te_x$
Autorzy:
Ciechan, A.
Winiarski, M.
Samsel-Czekała, M.
Powiązania:
https://bibliotekanauki.pl/articles/1431323.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Pq
74.25.Kc
74.62.F
74.70.Xa
Opis:
We study the electronic structure of iron-based superconductors $FeSe_{1-x}Te_x$ within the density functional theory. We pay particular attention to the pressure effects on the Fermi surface (FS) topology, which seem to be correlated with a critical superconducting temperature $T_C$ of iron chalcogenides and pnictides. A reduction of the FS nesting between hole and electron cylinders with increasing pressure is observed, which can lead to higher values of $T_C$. The tellurium substitution into selenium sites yields FS changes similar to the pressure effect.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 820-823
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity of Niobium Thin Films in the BiOCl/Nb Heterostructures
Autorzy:
Lotnyk, D.
Komanický, V.
Bunda, V.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1032733.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.F-
68.35.bg
74.45.+c
Opis:
In the current paper, electrical transport properties of 25 nm thick Nb films sputtered on the photosensitive semiconductor BiOCl were investigated in the temperature range 7.5 K ≤ T ≤8.5 K. The influence of green (532 nm) and red (640 nm) laser excitations on resistive superconducting transitions of the niobium thin films on a silicon glass and BiOCl single crystal substrates were studied. The temperature dependences of the resistivity for Nb are in good agreement with the McMillan model which indicates the strong influence of the inverse proximity effect induced by the interface. The increased influence of the BiOCl/Nb interface under laser excitation corresponds to the raising of the ratio of the density of normal to superconductivity carriers in the Tıghtarrow0 limit and this observation is in agreement with the photoconductivity study of BiOCl single crystals.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1030-1032
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Resistive Superconducting Transition of Bulk $(Bi_{0.6}Pb_{0.4})_2Sr_2Ca_2Cu_{3}O_{x}$
Autorzy:
Woch, W.
Chrobak, M.
Zalecki, R.
Kołodziejczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/1371417.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.F-
74.25.Uv
74.25.Wx
74.72.-h
64.60.F-
Opis:
The temperature widths of the resistive transition as well as the thermal fluctuations of bulk $(Bi_{0.6}Pb_{0.4})_2Sr_2Ca_2Cu_{3}O_{x}$ superconductor with $T_{c,50%}$ = 107.1 K were studied. The applied magnetic field widens the resistive transition according to the following formula: ΔT = $CH^{m} + ΔT_{0}$. The value of exponent m = 0.44 suggests that there is strong pining of vortices, especially at lower temperatures. The critical exponents λ of the conductivity were calculated using the following equation: Δσ = $Kε^{-λ}$, with the $λ_1$ = 1.75 close to the zero critical temperature and $λ_2$ = 3.77 at higher temperatures. These values were discussed within the available theoretical models.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 328-329
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studies on Isotope Shift Exponent and Pressure Coefficient for Extended Superconductors within BCS Formalism
Autorzy:
Banerjee, B.
Roy, S.
Powiązania:
https://bibliotekanauki.pl/articles/1808029.pdf
Data publikacji:
2009-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.+f
74.25.Bt
74.25.Ha
Opis:
A tight-binding model comprising a hopping and an attractive interaction term was considered for high temperature superconductors. Explicit calculations on the effects of isotopic substitution of atoms and application of pressure on the transition temperatures were made in this work. Exact analytical expressions for the isotope-shift exponent (α) and pressure coefficient $(γ_P)$ of transition temperature $(T_C)$ considering the isotopic mass and pressure dependence of the hopping and attractive interaction strengths from a minimal model describing superconductivity were obtained. Theoretical predictions for α and $γ_P$ with proper choice of parameters are found to be qualitatively consistent with the results of the experiments of high $T_C$ oxides. The results depend on the band dispersion chosen.
Źródło:
Acta Physica Polonica A; 2009, 115, 5; 914-919
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and physical properties of the new stannide Yb₃Pd₄Sn₁₃
Autorzy:
Gastaldo, F.
Giovannini, M.
Strydom, A.
Djoumessi, R.
Čurlík, I.
Reiffers, M.
Solokha, P.
Saccone, A.
Powiązania:
https://bibliotekanauki.pl/articles/1050753.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.27.+a
74.25.F-
74.10.+v
Opis:
Among the new discovered intermetallics in the Yb-Pd-Sn system, the cubic phase Yb₃Pd₄Sn₁₃, with a lattice parameter of 0.9743(5) nm, emerges as a new member of the R₃T₄Sn₁₃ family (R = rare earth element, T = transition metal) crystallizing in the Yb₃Rh₄Sn₁₃-structure type. The effective magnetic moment μ_{eff}=1.84 μ_{B}/Yb is strongly reduced. Moreover, measurements of magnetic properties, specific heat and resistivity indicate superconductivity below 2.4 K. This compound is found to exhibit a strongly enhanced electronic specific heat at low temperature from which we infer a possible low-lying magnetic phase transition or other source of magnetic entropy.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1006-1008
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Electrical Properties of SiC Grown by PVT Method in the Presence of the Cerium Vapor
Autorzy:
Avdonin, A.
Racka, K.
Tymicki, E.
Grasza, K.
Jakieła, R.
Pisarek, M.
Dobrowolski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1399070.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.F-
61.72.-y
81.10.Bk
61.72.uf
Opis:
The results of investigation of structural and electrical properties of bulk SiC crystals, which were grown by physical vapor transport method with different Ce impurity content added to the SiC source material, are presented. The gradual dosage of cerium from the SiC source and continuous presence of the cerium vapor over the SiC crystallization fronts during the crystal growth processes are confirmed. The cerium influences the overall concentration of structural defects. The increase of the concentration of both, donors and acceptors, and appearance of new shallow donors (15-32 meV) in 4H-SiC crystals are observed.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 761-764
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resistance and AC Susceptibility of YBCO 1:2:3 Films on Silver Substrates
Autorzy:
Zalecki, R.
Woch, W.
Chrobak, M.
Kołodziejczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/1431494.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.25.F
74.25.Ha
74.25.Sv
Opis:
The $YBa_{2}Cu_{3}O_{δ}$ films were obtained directly on the polished silver substrates by the sedimentation process. Thickness of these films is of the order of several tens micrometers. The temperature dependences of the resistance and the AC susceptibility of the films were measured and analyzed. The critical temperatures of these specimens vary from 89 K to 91 K and they do not depend on the annealing temperatures. The critical currents were calculated from AC susceptibility measurements using the Bean's model.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 850-853
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remarks on the Hall Conductivity in Chiral Superconductors: Weak vs. Strong Coupling Approach
Autorzy:
Rogatko, M.
Wysokiński, K.
Powiązania:
https://bibliotekanauki.pl/articles/1374790.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.25.F-
74.70.Pq
11.25.Tq
Opis:
We discuss the calculations of the ac Hall conductivity for superconductors with the time reversal symmetry breaking states. In the weak coupling theories these states show vanishing Hall response in one band models, even though one expects otherwise on symmetry grounds. On the other hand, the strong coupling approach based on the anti-de Sitter-conformal field theory correspondence leads to the non-vanishing Hall conductivity. We discuss the possible reasons of the discrepancy. The weak coupling many orbital theory leading to the Hall conductivity with correct temperature dependence is also briefly presented.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-9-A-12
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remarks on the First Hundred Years of Superconductivity
Autorzy:
Wysokiński, K.
Powiązania:
https://bibliotekanauki.pl/articles/1431128.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
01.65.+g
74.25.Bt
74.25.F-
Opis:
On the occasion of centenary of superconductivity discovery I recall some facts from the first period and attempts to understand the phenomenon. It turns out that most famous physicists of the first half of XX century have tried to solve the puzzle. Bardeen, Cooper and Schrieffer succeeded in 1957. The BCS theory successfully described all known facts and offered new predictions, which soon have been confirmed experimentally contributing to the widespread acceptance of the theory. It have found applications in nuclear physics, theory of neutron stars and cold atomic gases. The discoveries of new superconductors in the last thirty years show that simple BCS model is not enough to understand new unconventional superconductors. The studies of superconductors develop vividly and still fascinate new generations of physicists working in such diverse fields as material science and string theory.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 721-725
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physical Properties of "HTSC/Photosemiconductor" Micro- and Nanoplates Based Junctions
Autorzy:
Bunda, V.
Bunda, S.
Vashchuk, F.
Feher, A.
Kováč, J.
Powiązania:
https://bibliotekanauki.pl/articles/1535401.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.25.Hv
74.45.+c
74.25.F-
74.55.+v
Opis:
In this paper we report the formation process and electrophysical properties of 'high temperature superconductor $(YBa_2Cu_3O_{7 - x})$/photosemiconductor (BiOCl:Ti)' micro- and nanoplates based junction. The energy band model of ≪HTSC-semiconductor≫ junction is proposed.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1040-1041
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:
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

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