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Wyszukujesz frazę "74" wg kryterium: Temat


Tytuł:
Clean bulk YBaCuO superconductors doped by paramagnetic ions of Sm and Yb
Autorzy:
Jirsa, M.
Volochová, D.
Kováč, J.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1054700.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Op
74.25.Sv
74.60.Ge
74.72.-h
Opis:
The recently developed clean cuprate technology was employed to study the effect of tiny amounts of paramagnetic Yb and Sm ions on electromagnetic properties of bulk YBaCuO. Small samples of about 1.5×1.5×0.5 mm³ were measured by vibrating sample magnetometer in the field range ±9 T and temperatures 30 K to 10 K in the non-superconducting tetragonal state and 300 K to 70 K in the orthorhombic, superconducting state. In the latter case, we observed the reversible paramagnetic moment above T_{C}, similar as in the tetragonal state. Below T_{C} an irreversible magnetic moment was observed from which critical current density, J_c, was evaluated using the extended Bean model. The effect of doping by Yb and Sm ions on J_c was studied and a correlation between J_c and the total paramagnetic moment was found. Both J_c(B) and the normalized pinning force density as a function of the reduced magnetic field were analyzed in terms of the classical model and discussed with respect to the material anisotropy, giving us at least a rough idea on the type of the effective pinning type and mechanism.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1027-1029
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoresistance study of c-axis oriented YBCO thin film
Autorzy:
Chrobak, M.
Woch, W.
Kowalik, M.
Zalecki, R.
Giebułtowski, M.
Przewoźnik, J.
Kapusta, Cz.
Szwachta, G.
Powiązania:
https://bibliotekanauki.pl/articles/1054863.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.78.-w
74.25.Op
74.25.Qt
74.78.Bz
Opis:
The c-axis orientation YBa₂Cu₃O_δ thin film was prepared directly on MgO substrate by the pulse laser deposition. The thickness of the film is 170 nm. The superconducting critical temperature is T_{c50%}=87.5 K and the width of superconducting transition is ΔT = 1.8 K. The temperature dependences of magnetoresistance were measured up to 90 kOe. The widths of the transition to the superconducting state versus applied magnetic field were derived and they were fitted using the formula: Δ T=CH^m +Δ T₀. The irreversibility fields as a function of temperature were obtained and fitted by the de Almeida and Thouless-like equation: H_{irr}=H_{irr0}(1-T/T_{c0})^n. The irreversibility field at the liquid nitrogen temperature was calculated and it is H_{irr}=43.8 kOe when the applied magnetic field is parallel to the c-axis.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1018-1020
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Fulde-Ferrell-Larkin-Ovchinnikov Superconductivity in Disordered Systems
Autorzy:
Ptok, A.
Powiązania:
https://bibliotekanauki.pl/articles/1537270.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Fg
74.20.Mn
74.20.Rp
74.25.Dw
74.81.-g
Opis:
The Fulde-Ferrell-Larkin-Ovchinnikov phase, with a spatially oscillating order parameter, may be induced by strongly magnetic field at low temperature. It is believed that the Fulde-Ferrell-Larkin-Ovchinnikov phase can exist only in homogeneous superconductors, and even weak impurity potential can lead to its destruction. The analysis of the Fulde-Ferrell-Larkin-Ovchinnikov phase in the Bogoliubov-de Gennes equation shows however, that this phase can exist in the presence of weak disorder. Using Bogoliubov-de Gennes equations, we discussed the influence of diagonal and off-diagonal disorder on the Fulde-Ferrell-Larkin-Ovchinnikov phase.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 420-422
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vortex Motion and Quasiparticle Resistivity in Superconductors at Microwave Frequencies
Autorzy:
Sarti, S.
Amabile, C.
Fastampa, R.
Giura, M.
Silva, E.
Pompeo, N.
Powiązania:
https://bibliotekanauki.pl/articles/2047225.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Nf
74.20.De
74.60.Ge
74.70.Ad
74.72.-h
Opis:
At nonzero frequencies both the normal and superfluid fractions, as well as moving vortices, contribute to the electrical transport, resulting in intricate expressions for the resistivity. We present an extended study of microwave resistivity data measured on YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$, SmBa$\text{}_{2}$ Cu$\text{}_{3}$O$\text{}_{7-δ}$, and MgB$\text{}_{2}$ by means of a broad-band technique between 2 and 20 GHz and of a resonant system at 50 GHz. We discuss the main experimental fingerprints that allow one to identify the relevance of the different contributions from the measured microwave response as a function of frequency, temperature, and magnetic field. We show that the field-dependent superfluid/quasiparticles dynamics cannot be in general neglected with respect to the vortex motion, albeit its relative importance is different in different materials: in high temperature superconductors vortex motion prevails at high fields, but at low fields a significant superfluid/quasiparticle contribution exists (ascribed to the presence of lines of nodes). In MgB$\text{}_{2}$ the two contributions are comparable even at high fields. In this general frame, we derive from the measurements vortex and superfluid parameters in agreement with theoretical predictions and independent measurements.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 87-93
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Obtaining a Rough Flux Front in Type-II Superconductors Using a Critical State Model
Autorzy:
Romero-Salazar, C.
Hernández-Flores, O.
Chabanenko, V.
Kuchuk, E.
Abaloszewa, I.
Nabialek, A.
Pérez-Rodríguez, F.
Powiązania:
https://bibliotekanauki.pl/articles/1398648.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.20.De
74.25.Ha
74.25.N-
74.25.Op
74.25.Sv
74.25.Wx
74.62.Dh
74.81.-g
Opis:
In this work we numerically modelled a periodic magnetic flux pattern which qualitatively reproduces the so-called sand avalanches scenario in type-II superconductors. To model these sand-pile patterns we consider a perturbation on the critical current which, as a first approximation, follows a periodic function which depends on the position.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 645-648
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanostructural Superconducting Materials for Fault Current Limiters and Cryogenic Electrical Machines
Autorzy:
Prikhna, T.
Gawalek, W.
Savchuk, Ya.
Sergienko, N.
Moshchil, V.
Sokolovsky, V.
Vajda, J.
Tkach, V.
Karau, F.
Weber, H.
Eisterer, M.
Joulain, A.
Rabier, J.
Chaud, X.
Wendt, M.
Dellith, J.
Danilenko, N.
Habisreuther, T.
Dub, S.
Meerovich, V.
Litzkendorf, D.
Nagorny, P.
Kovalev, L.
Schmidt, Ch.
Melnikov, V.
Shapovalov, A.
Kozyrev, A.
Sverdun, V.
Kosa, J.
Vlasenko, A.
Powiązania:
https://bibliotekanauki.pl/articles/1549637.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Sv
74.81.Bd
74.70.Ad
74.78.Na
74.62.Fj
74.25.Ld
74.62.Dh
74.25.Ha
Opis:
Materials of the Y-Ba-Cu-O (melt-textured $YBa_{2}Cu_{3}O_{7-δ}$-based materials or MT-YBCO) and Mg-B-O ($MgB_{2}$-based materials) systems with high superconducting performance, which can be attained due to the formation of regularly distributed nanostructural defects and inhomogeneities in their structure can be effectively used in cryogenic technique, in particular in fault current limiters and electrical machines (electromotors, generators, pumps for liquid gases, etc.). The developed processes of high-temperature (900-800°C) oxygenation under elevated pressure (16 MPa) of MT-YBCO and high-pressure (2 GPa) synthesis of $MgB_{2}$-based materials allowed us to attain high superconductive (critical current densities, upper critical fields, fields of irreversibility, trapped magnetic fields) and mechanical (hardness, fracture toughness, Young modulus) characteristics. It has been shown that the effect of materials properties improvement in the case of MT-YBCO was attained due to the formation of high twin density (20-22 $μm^{-1}$), prevention of macrocracking and reduction (by a factor of 4.5) of microcrack density, and in the case of $MgB_{2}$-based materials due to the formation of oxygen-enriched as compared to the matrix phase fine-dispersed Mg-B-O inhomogeneities as well as inclusions of higher borides with near-$MgB_{12}$ stoichiometry in the Mg-B-O matrix (with 15-37 nm average grain sizes). The possibility is shown to obtain the rather high $T_{c}$ (37 K) and critical current densities in materials with $MgB_{12}$ matrix (with 95% of shielding fraction as calculated from the resistant curve).
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 7-14
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Ratio of the Energy Gap Amplitude to the Critical Temperature for Cuprates
Autorzy:
Szczęiśniak, R.
Durajski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1382034.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.20.Fg
74.20.Mn
74.25.Bt
74.72.-h
74.72.Bk
74.72.Jt
Opis:
The model for the cuprates based on the modified electron-phonon pairing mechanism has been tested. For this purpose, the superconductors with high value of the critical temperature have been taken into consideration. In particular: $YBa_{2}Cu_{3}O_{7-y}$, $HgBa_{2}CuO_{4+y}$, $HgBa_{2}Cu_{1-x}Zn_{x}O_{4+y}$, and $HgBa_{2}Ca_{2}Cu_{3}O_{8+y}$. It has been shown that the dependence of the ratio $R_{1}$ ≡ $2Δ_\text{tot}^{(0)}$/$k_{B}T_{C}$ on the doping (p) can be properly predicted in the framework of the presented theory; the symbol $Δ_\text{tot}^{(0)}$ denotes the energy gap amplitude at the temperature of zero kelvin, and $T_{C}$ is the critical temperature. The numerical results have been supplemented by the formula which describes the function $R_{1}(p)$.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-92-A-96
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
d-Wave Superconductivity in a System with Open Boundary Conditions
Autorzy:
Pisarski, P.
Harań, G.
Powiązania:
https://bibliotekanauki.pl/articles/2041464.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Rp
74.72.-h
74.78.Na
74.81.-g
Opis:
We discuss the d-wave superconductivity in confined geometry by imposing open boundary conditions on the attractive Hubbard model. Within the Bogoliubov-de Gennes approach we evaluate the order parameter and charge density distribution in the system.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 721-725
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Current Problems in HTc Superconductors
Autorzy:
Sosnowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1536989.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.25.Wx
74.25.Sv
74.25.Uv
Opis:
New results of the investigations critical current problems in the high temperature oxide superconductors are presented, basing on the flux pinning analysis. Model of the pinning interaction of the nanosized centers with pancake vortices is proposed, while comparison of the received results concerning the dependence of the potential barrier versus transport current with other pinning forces approaches is presented. Special attention is devoted to the investigations of the influence the initial position of the vortex captured at pinning center on the current-voltage characteristics and critical current.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 328-330
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Multiple Phase Slip Phenomena in the Narrow Superconducting Channels
Autorzy:
Baranov, V.
Balanov, A.
Kabanov, V.
Powiązania:
https://bibliotekanauki.pl/articles/1426736.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.40.Gh
74.81.-g
74.78.Na
74.40.De
Opis:
The current-voltage characteristic of the narrow superconducting channel is investigated by direct numerical integration of the time-dependent Ginzburg-Landau equations. We have demonstrated that the steps in the current-voltage characteristic correspond to a number of different bifurcation points of the time-dependent Ginzburg-Landau equations. We have analytically estimated the period and the averaged voltage of the oscillating solution for the relatively small currents. We have also found the range of currents where the system transforms to the chaos.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1038-1041
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:
Investigation Details of Vortex Density in Laser-Written Π-Shaped Channel of YBCO Bridge by Means of I-V Dependences
Autorzy:
Steponaviciene, L.
Sulcas, J.
Jukna, A.
Jung, G.
Plausinaitiene, V.
Abrutis, A.
Maneikis, A.
Gong, M.
Sobolewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1505530.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
74.25.Sv
74.25.F-
74.25.Wx
Opis:
A current-self-induced magnetic field $H_{j}$, such that $H_{c1} < H_{j} < H_{c2}$ at $T < T_{c}$, penetrates a thin-film, type-II superconductor forming the Abrikosov magnetic vortex-antivortex pairs in the film's areas of weakest superconductivity. Our atomic force microscopy and scanning tunneling microscopy images confirm that in 50 μm wide, 100 μm long and 0.3 μm thick $YBa_2Cu_3O_{7 - x}$ superconducting devices magnetic flux penetrates first into a 5 μm wide, Π-shaped and partially deoxygenated (x ≈ 0.2) channel for easy vortex motion. When the Lorentz force overcomes pinning force in the channel, the flux starts to move and its drift dissipates energy inducing dc voltage. This work reports on the density of coherently moving vortices along the channel vs. temperature in range from $0.93T_{c}$ to $0.97T_{c}$. Our simulations show that the vortex density vs. temperature dependence extracted from I-V measurements of our devices follows the temperature dependence of magnetic field penetration depth and the coherence length of the superconductor.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 180-182
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Current Distribution in Y-Ba-Cu-O Superconducting Microbridges Containing Π-Shaped Channel for Easy Vortex Motion
Autorzy:
Sulcas, J.
Steponaviciene, L.
Jukna, A.
Jung, G.
Plausinaitiene, V.
Abrutis, A.
Gong, M.
Sobolewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1505543.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
74.25.Sv
74.25.F-
74.25.Wx
Opis:
A mixed state in dc-biased thin films of II-type superconductors realizes the Abrikosov magnetic vortices/antivortices, which are the result of the current-self magnetic field penetration into the film at temperatures lower than its critical temperature $T_{c}$. A nucleation of vortices/antivortices at the superconducting film's edges, their motion perpendicular to the direction of biasing current, and the annihilation in the film's center originates from a current dissipation in the superconductor and expresses itself in experiments as a dc voltage. This work reports on the results of simulation of current density in a 50 μm wide, 100 μm long, and 0.3 μm thick $YBa_2Cu_3O_{7 - x}$ microbridges containing Π-shaped 5 μm wide single channel of easy vortex motion fabricated by means of laser-writing technique. Analyzing a two-dimensional-net of resistors and assuming that, due to the Meissner-Ochsenfeld effect, the magnetic flux penetration into superconducting film is nonlinear, we demonstrate that presence of a Π-shaped channel causes a non-homogeneous distribution of current in the microbridge.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 183-185
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved Transresistance Characteristics of Inductance-gate Type SFFT Using AFM Lithography
Autorzy:
Ko, S.
Powiązania:
https://bibliotekanauki.pl/articles/1400571.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Pq
74.25.F-
74.25.Jb
74.55.+V
Opis:
An atomic force microscope (AFM) was used to locally anodize the serial channels of an inductance-gate type superconducting flux flow transistor (SFFT) as narrow slits with a width of 50 μm, a space of 25 μm, and 12 turns, to improve the transresistance value. Among the serial channels that were anodized with the scanning tip of the AFM in the drain current line, channels 1 and 2 were 7.3 and 7.9 μm wide, and 531 and 461 nm high, respectively. The critical current density in the serial channel of the fabricated SFFT, which was determined using an AFM modification method, was decreased by increasing the gate current. The measured current-voltage curves were compared with the simulated ones. The maximum transresistance value was 0.56 Ω at the drain current of 20 mA when the gate current was 6 mA. The transresistance characteristics of the inductance-gate type SFFT could be more improved than that of the single-channel type SFFT using an inductively coupled plasma lithography method
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 928-930
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vortex Pinning in Ferromagnet/Superconductor Bilayers - the Dependence on the Ferromagnetic Layer and Temperature
Autorzy:
Adamus, Z.
Cieplak, M. Z.
Abal'oshev, A.
Berkowski, M.
Kończykowski, M.
Cheng, X. M.
Shu, L. Y.
Chien, C. L.
Powiązania:
https://bibliotekanauki.pl/articles/2046703.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Qt
74.78.Db
74.78.Fk
Opis:
The behavior of vortex pinning induced by the magnetic domain reversal is studied in the ferromagnet/superconductor bilayers in which superconducting film is niobium and the ferromagnetic layers are the Co/Pt superlattices with perpendicular magnetic anisotropy. The local magnetic field across narrow ferromagnet/superconductor bilayer stripe is measured using a line of miniature Hall sensors. The pinning is studied for samples with different amount of repeats of Co/Pt superlattice, and as a function of temperature.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 451-456
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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