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Wyświetlanie 1-15 z 37
Tytuł:
Analysis of Electromagnetic Phenomena in HTc Superconductors
Autorzy:
Sosnowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1812341.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Qt
74.25.Sv
Opis:
Unique electromagnetic properties, especially concerning recent observations of the giant remanent magnetic moment in HTc superconductors, require new approach to modeling these phenomena in the oxide ceramics. The present paper is devoted to the analysis of the influence of flux pinning on critical current and flux trapping in HTc superconductors. Modeling of the interaction between nanosized pinning centers and pancake vortices is presented, allowing to determine critical current density, taking into account elasticity forces of the vortices lattice. Ceramic structure of oxide superconductors was considered in trapped flux analysis. The mechanism of trapped flux generation was regarded as strongly related to vortex pinning and critical current phenomena.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 269-274
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Contactless Estimation of Critical Current Density and Its Temperature Dependence Using Magnetic Measurements
Autorzy:
Youssef, A.
Baničová, L.
Švindrych, Z.
Janů, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1535392.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
74.25.Sv
Opis:
We have measured magnetic response of second-generation high temperature superconductor $YBa_2Cu_3O_{x}$ wire and Nb thin film in perpendicular ac field as a function of temperature. We compare experimental complex ac susceptibility to the calculated susceptibility based on the model of Bean's critical-state response in two-dimensional disk in perpendicular field. The harmonic analysis is needed for comparison between the model and the experimental data. We present a method of linking model and experimental susceptibility. Good agreement of experimental susceptibility with model susceptibility of 2D disk allows contactless estimation of critical depinning current density and its temperature dependence.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1036-1037
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of the Magnetic Field on the Dynamics of the Flux Jumps in the Flux Flow Model
Autorzy:
Vasiliev, S.
Nabiałek, A.
Rusakov, V.
Belevtsov, L.
Chabanenko, V.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1537020.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Sv
74.70.Ad
Opis:
We studied the dynamics of the flux jumps in type II superconductors assuming this dynamics to be determined by magnetic diffusion. The conductivity of the sample during the jump was described by the flux flow conductivity, which depends on local magnetic field. We solved this problem numerically for an infinite slab sample. We assumed that superconducting sample was fully penetrated by the magnetic flux at the beginning and that the local induction of the magnetic field, in the whole sample, was equal to $B_0$. Then, the external magnetic field was increased by a value of $ΔB_{a}$ and in the external magnetic field of $B_0 + ΔB_{a}$ flux jump occurred. In our simulations we used the parameters characteristic of a conventional NbTi superconductor at 4.2 K. In particular, we studied the influence of the parameter B_0 on the flux jumps' dynamics. We have found that this parameter strongly influences initial stage of the diffusion process. With increasing $B_0$, the time during which flux front of the avalanche reaches the center of the sample decreases. The results of numerical simulations were compared with experiments.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 340-342
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of Magnetic History on the Stability of Critical State and the Dynamics of Flux Jumps in Conventional NbTi Superconductor
Autorzy:
Nabiałek, A.
Vasiliev, S.
Chabanenko, V.
Perez-Rodriguez, F.
Piechota, S.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1537035.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Ad
74.25.Sv
Opis:
We studied the influence of magnetic history on the stability of critical state and the dynamics of flux jumps in conventional NbTi superconductor. We have found that both the stability of critical state and the dynamics of flux jumps are strongly influenced by the magnetic history and by the magnetic field distribution induced within the sample by preceding jumps. This magnetic field distribution can be particularly complex in the region of the hysteresis loop where the external magnetic field changes its sign (region of remagnetization), because of demagnetizing effects. For this reason, the most complex structure of the flux jumps is observed in the third quadrant of magnetization hysteresis loop. Flux jumps observed in the region of remagnetization have different dynamics in comparison to the jumps observed in other regions of the magnetization hysteresis loop. Duration of these jumps is usually significantly longer than others, and their structure is more complex.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 343-345
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical State Stability and Flux Jumps Dynamics in a Single Crystal of $YBa_{2}Cu_{3}O_{7-δ }$
Autorzy:
Nabiałek, A.
Vasiliev, S.
Chabanenko, V.
Yao, X.
Cai, Y.
Guo, L.
Kuzovui, M.
Powiązania:
https://bibliotekanauki.pl/articles/1431339.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.25.Sv
Opis:
We studied the critical state stability and the dynamics of the flux jumps, caused by thermomagnetic avalanches, in a large (3× 3× 1 $mm^{3}$) single crystal of $YBa_{2}Cu_{3}O_{7-δ }$ superconductor. Flux jumps were observed only at the lowest temperatures attainable in our system (at about 2.2 K) and for the external magnetic field parallel to the c-axis of the investigated crystal. It is shown that thermomagnetic avalanches are initiated in dynamic conditions, for which the magnetic diffusivity is much smaller than the thermal diffusivity. For large single crystals of $YBa_{2}Cu_{3}O_{7-δ }$ immersed directly in liquid helium, the analysis of the critical state stability can be performed in isothermal approximation. However, the conditions of the critical state stability can change dramatically by improving the thermal isolation between the sample and the surrounding coolant. The dynamics of the flux jumps was analyzed in the framework of the model of magnetic diffusion. It is shown that the magnetic diffusivity changes dramatically during the process of the thermomagnetic avalanche. We also studied the influence of the external magnetic field and of the magnetic history on the duration of the flux jumps.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 836-840
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Nano-SiC Doping on the Superconducting Critical Parameters in $MgB_2$/Fe Wires and Tapes
Autorzy:
Gajda, D.
Zaleski, A.
Morawski, A.
Kario, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813696.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Ad
74.25.Sv
Opis:
In this paper the results of critical current measurements for $MgB_2$ wires and tapes in iron sheath with and without nano-SiC doping are presented. We focus on power-in-tube processing technique, using both in situ and ex situ methods. In situ $MgB_2$ wires and tapes were fabricated from $MgH_2$ and B or Mg and B powders. The methods such as hydrostatic extrusion and rolling were used. The samples were annealed under high Ar gas pressure (hot isostatic pressing) at 750°C and 1.0 GPa for 40 min. It was found that critical current of $MgB_2$/Fe superconducting wire or tape with nano-SiC dopant increased in higher magnetic field values in comparison to pure $MgB_2$. A significant difference of $J_c$ in tapes made by in situ way from $MgH_2$ and Mg were found.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 371-374
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pinning improvement of A15 applied superconducting materials
Autorzy:
Glowacki, B.
Powiązania:
https://bibliotekanauki.pl/articles/1062056.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Wx
74.25.Sv
74.25.Op
Opis:
Electron-phonon coupling is one of the most common interaction in superconducting materials ranging from Nb₃Sn, MgB₂, iron-based superconductors and high temperature cuprates such as YBa₂Cu₃O_{7-δ} and HgBa₂Ca₂Cu₃O_{8+δ}. However an importance of the electron-phonon coupling constant, λ_{ep}, should not be underestimated for characterisation of the electronic properties of superconducting materials, but it is important that the enhanced flux pinning mechanism can be hold responsible for the applicability of the A15 superconducting materials in emerging hydrogen cryomagnetic technology where temperature of the liquid H₂ can be as low as 14 K.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 531-536
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fluxonic Properties of Vortices in a Washboard Pinning Potential Fabricated by Focused Particle Beam Techniques
Autorzy:
Dobrovolskiy, O.
Huth, M.
Shklovskij, V.
Powiązania:
https://bibliotekanauki.pl/articles/1490776.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.F-
74.25.Wx
74.25.Sv
Opis:
A challenging aspect of the usage of patterned nanostructures relates to the development of superconducting devices operating with the Abrikosov vortices in some pinning potential. To provide such a potential we have used thin epitaxial films of Nb with washboard-like nanostructures in the form of grooves or Co stripes. The nanostructures were prepared by focused ion beam milling or focused electron beam induced deposition, respectively. The results of transport measurements affirm the existence of two fluxonic effects, the guided vortex motion and the vortex ratchet effect, both invoked by the nanostructuring. In particular, the effects represent the basis for the development of advanced fluxonic devices using a directional or orientational control of the net vortex motion in Nb films nanostructured by focused particle beam techniques.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 82-84
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability of Bilayer Superconductors against Thermomagnetic Avalanche
Autorzy:
Vasiliev, S.
Chumak, O.
Chabanenko, V.
Pérez-Rodríguez, F.
Nabiałek, A.
Powiązania:
https://bibliotekanauki.pl/articles/1374778.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Op
74.72.-h
74.25.Sv
Opis:
The problem of stability of bilayer type II superconductor with different critical current densities of inner part and coating was considered. The optimum thickness of surface layer enabling the maximal increase of the field of first flux jump was found. The field of instability for such bilayer structure was calculated for NbTi superconductor. An increase of the field of the first flux jump by about 60% has been found for optimal coating thickness.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-84-A-87
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kim-Type Critical State Models and Critical Currents of Thallium Based Superconductors
Autorzy:
Woch, W.
Zalecki, R.
Kołodziejczyk, A.
Heiml, O.
Sudra, H.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/1812280.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.Jt
74.25.Sv
74.25.Ha
Opis:
The two extended formulae in the power form of the Kim critical state model were used to fit the critical currents versus the dc applied magnetic field. Two samples of thallium based superconductors: the $(Tl_{0.6}Pb_{0.24}Bi_{0.16})$$(Sr_{0.9}Ba_{0.1})_2Ca_2Cu_3O_y$ film on single-crystalline lanthanum aluminate and the bulk $(Tl_{0.5}Pb_{0.5})Sr_2(Ca_{1.8}Gd_{0.2})Cu_2O_y$ were chosen to test the models. The formulae were compared to the percolation model described by the exponential expression. The first model fits the experimental data better for the thallium based film whereas the second approach is better for the thallium based bulk sample.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 99-106
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Easy Vortex Motion in an Artificial Channel of $YBa_2Cu_3O_{7-δ}$ Superconducting Films
Autorzy:
Jukna, A.
Barboy, I.
Jung, G.
Abrutis, A.
Li, X.
Wang, D.
Sobolewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1813381.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Sv
74.25.Qt
74.78.Bz
Opis:
Quasi-Josephson effect produced by a coherent vortex motion in the horizontal part of the laser-performedΠ-shaped channel of a $YBa_2Cu_3O_{7-δ}$ superconducting bridge was investigated by means of electric transport measurements. We observed that in our structures, in a limited range of temperatures and bias currents, the vortices were confined in the channel only and moved coherently with the velocity of $3×10^4$ m/s. The corresponding current-voltage characteristics of the bridge exhibited Josephson-like voltage steps with the amplitude dependent on temperature, but independent of the bias current.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 959-962
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Current Density and Microstructure of $NdBa_2Cu_3O_7$ Single Crystal
Autorzy:
Diko, P.
Zmorayová, K.
Šefčiková, M.
Antal, V.
Kováč, J.
Yao, X.
Powiązania:
https://bibliotekanauki.pl/articles/1535339.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Sv
74.62.Bf
Opis:
The top-seeded solution growth method was used to grow NdBCOss single crystals in air. The microstructure of the samples has shown that the oxygenation crack structure developed in the single crystals. The intrinsic critical current density was estimated to be at least twice higher than the value of volume critical current density determined from the magnetization measurements.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1028-1030
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Resistive Superconducting Transition of a $(Tl_{0.6}Pb_{0.24}Bi_{0.16})(Ba_{0.1}Sr_{0.9})_2Ca_2Cu_3O_{y}$ Film
Autorzy:
Woch, W.
Chrobak, M.
Kołodziejczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/1537158.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Uv
74.25.Sv
74.20.De
Opis:
In this paper we analyze the resistive transition as a function of both the temperature and the dc applied magnetic field. We use the two models: first, based on the Ambegaokar and Halperin theory that describes the resistive transitions by the modified Bessel function and second, based on the Anderson and Kim theory represented by the exponential formula. The fits of the models to experimental results show that the freezing into superconducting vortex-glass phase takes place at the same temperature that does not practically depend on the applied magnetic field.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 389-392
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Current Problems in Neutrons Irradiated HTc Multilayered Superconductors
Autorzy:
Sosnowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1398613.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.25.Wx
74.25.Sv
Opis:
In the paper there is given an analysis of the critical current problems in irradiated multilayered high temperature oxide superconductors. Critical current for the direction of current flow inside the layers is investigated basing on analysis of the capturing interaction of pancake vortices with nanodefects, created by fast neutrons irradiation. Analysis of the pinning potential barrier formation is presented. From performed calculations of current-voltage characteristics fitted to measurements the inherent pinning centers concentration and their average dimensions were estimated. The case of perpendicular to layers current has been regarded too, taking into account the intrinsic Josephson junctions formation. The influence of nanodefects concentration on the Josephson penetration depth has been considered, whose length determines the Swihart velocity and current-voltage characteristics of junction.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 585-587
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of Hotspot Formation in Nanostructured Superconducting Stripes Excited with Single Photons
Autorzy:
Jukna, A.
Kitaygorsky, J.
Pan, D.
Cross, A.
Perlman, A.
Komissarov, I.
Sobolewski, R.
Okunev, O.
Smirnov, K.
Korneev, A.
Chulkova, G.
Milostnaya, I.
Voronov, B.
Gol'tsman, G.
Powiązania:
https://bibliotekanauki.pl/articles/1813380.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Fy
74.25.Sv
74.45.+c
Opis:
Dynamics of a resistive hotspot formation by near-infrared-wavelength single photons in nanowire-type superconducting NbN stripes was investigated. Numerical simulations of ultrafast thermalization of photon-excited nonequilibrium quasiparticles, their multiplication and out-diffusion from a site of the photon absorption demonstrate that 1.55 μm wavelength photons create in an ultrathin, two-dimensional superconducting film a resistive hotspot with the diameter which depends on the photon energy, and the nanowire temperature and biasing conditions. Our hotspot model indicates that under the subcritical current bias of the 2D stripe, the electric field penetrates the superconductor at the hotspot boundary, leading to suppression of the stripe superconducting properties and accelerated development of a voltage transient across the stripe.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 955-958
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 37

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