Temat: 74.25.Ha - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Superconducting and Magnetic Phases with 1212-Type of Structure
Autorzy:: Khlybov, E. P.
Kostyleva, I. E.
Nenkov, K.
Nizhankovskii, V. I.
Palewski, T.
Warchulska, J.
Tematy:: 74.25.Ha
74.72.Jt; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2012971.pdf Link otwiera się w nowym oknie
Opis:: Studies of magnetic and transport properties of the 1212 compounds MA'$\text{}_{2}$A''Cu$\text{}_{2}$O$\text{}_{7-x}$ (M 3D Al or Tl; A'= Sr or Ba; A''= RE, Y, and Ca) revealed a number of interesting magnetic phenomena. Apart from high-temperature superconductivity, these compounds exhibit spontaneous antiferromagnetism, field induced antiferromagnetism or ferromagnetism. The different magnetic orders and superconductivity may be realized in the same compound as a result of the phase separation.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Magnetic Properties of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ Melt Textured Samples Prepared by Powder Melting Process and Quench and Melt Growth Techniques
Autorzy:: Plesch, G.
Cígaň, A.
Maňka, J.
Bučkuliaková, A.
Hanic, F.
Buchta, Š.
Andrzejewski, B.
Stankowski, J.
Tematy:: 74.25.Ha
74.80.Bj; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2014193.pdf Link otwiera się w nowym oknie
Opis:: The microstructure and magnetic properties of the melt textured YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ samples prepared by the powder melting process, in which Y$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{5}$ and BaCuO$\text{}_{2}$ were used as precursors, and those prepared by the quench and melt growth method are described and compared. The lattice parameters and T$\text{}_{c}$ values for the samples prepared by the both techniques were similar. The penetration and the spatial distribution of the magnetic flux in the superconducting samples was imaged by means of a field-mapping device using a Hall probe. In the range of low magnetic fields up to 820Am$\text{}^{-1}$ no significant differences in penetration of magnetic flux between the samples prepared by the powder melting process and the quench and melt growth were observed. The mapping could not resolve any grain boundaries, single grains and structural defects. By the ac and virgin volume magnetisation characteristics, which were measured in the zero-field cooled condition by a 2nd order SQUID gradiometer, no weak links were identified. Better magnetic properties of the quench and melt growth samples in high magnetic fields can be explained by the differences in microstructure and/or by the risen content of the finely dispersed 211 and Pt containing phases. The increase factor in magnetisation is about 2.5. Some aspects of the Bean model for textured YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ samples are discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Magnetic Field Influence on the Superconducting Transition in Granular (BiPb)-Sr-Ca-Cu-O Superconductors
Autorzy:: Gazda, M.
Klimczuk, T.
Tematy:: 74.81.Bd
74.25.Ha; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1537091.pdf Link otwiera się w nowym oknie
Opis:: In this work we present the studies of the influence of magnetic field on the superconducting transition in granular (Bi,Pb)-Sr-Ca-Cu-O superconductors. Special attention was devoted to the samples containing relatively small granules (smaller than 30 nm) of the 2212 superconducting phase. The samples were obtained by the glass-ceramic technology. The transition into the superconducting state was observed in the samples containing the 2212 phase in the form of crystallites with dimension equal or larger than 20 nm. Typical for granular superconductors, a two-stage character of the superconducting transition has been observed. Magnetic field influences the temperature dependence of resistivity of the samples containing granules of the 2212 phase in the superconducting phase, also in case of the samples for which no transition in the R(T) plot is observed. In the studied samples the magnetoresistance was positive in the whole range of magnetic fields.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Vortex Properties in a Model with Local Pairs
Autorzy:: Śledź, Ż.
Mierzejewski, M.
Maśka, M. M.
Tematy:: 74.25.Ha
74.20.-z; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2046800.pdf Link otwiera się w nowym oknie
Opis:: We investigate the vortex structure in the Penson-Kolb model with and without impurities. We focus on the consequences arising from the non-local field-dependent pairing interaction for the vortex profile, current distribution, and the local density of states.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Experimental Studies of Electronic Phase Separation in High Temperature Superconductors
Autorzy:: Szymczak, H.
Szymczak, R.
Tematy:: 74.25.Ha
74.72.-h; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1860950.pdf Link otwiera się w nowym oknie
Opis:: Experimental research on macroscopic phase separation in La$\text{}_{2}$CuO$\text{}_{4+\delta}$ superconductor and photo-doped cuprates is reviewed. It is shown that the properties of the mixed-phase state strongly depend on the shape and size of the phase domains formed during the phase separation process. The interplay of magnetic and superconducting properties in the mixed-phase state is considered in details. The mechanisms driving the phase separation in La$\text{}_{2}$CuO$\text{}_{4}$ and photo-doped materials are discussed in connection with presented experimental results.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Multi-Band Calculations on the Upper Critical Fields of Iron Pnictide Superconductor $Ba(Fe_{1-x}Ni_x)_2As_2$ (x=0.072)
Autorzy:: Huang, Hai
Lv, Peng-Li
Li, Wei-Feng
Liu, Peng
Tematy:: 74.25.Ha; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1399148.pdf Link otwiera się w nowym oknie
Opis:: Based on two-band Ginzburg-Landau theory, we study the upper critical fields for the overdoped composition of the iron-based superconductor $Ba(Fe_{1-x}Ni_x)_2As_2$ with x=0.072. All the temperature and angular results of this compound are consistent with the experimental data. Thus our analysis strongly suggests that $Ba(Fe_{1-x}Ni_x)_2As_2$ in the overdoped regime is a two-gap superconductor.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Magnetization, Susceptibility and Critical Currents of $(Tl_{2-x}Re_{x})Ba_{2}CaCu_{2}O_{y}$ Thin Films
Autorzy:: Woch, W.
Dujavová, A.
Przewoźnik, J.
Zalecki, R.
Kołodziejczyk, A.
Sojková, M.
Chromik, Š.
Tematy:: 70.72.Gr
74.25.Ha; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1431480.pdf Link otwiera się w nowym oknie
Opis:: The magnetization and the AC susceptibility vs. the temperature as well as the applied magnetic field of the thin film $(Tl_{2-x}Re_{x})Ba_{2}CaCu_{2}O_{y}$ with x=0 and 0.15 on R-plane sapphire substrate with $CeO_{2}$ buffer layer were measured and analyzed. XRD measurements show c-axis as well as a-b plane oriented Tl-1212 and superconducting pure phase. The zero critical temperature of the Tl-Re sample is 99.9 K and is practically the same as the critical temperature of the rhenium free sample: 99.5 K. The Tl-Re superconductor exhibits two peaks of the absorption part of AC susceptibility in the vicinity of the critical temperature in contrary to the rhenium free sample. The first peak placed in higher temperature is related to intragranular properties while the second peak is connected with the intergranular one. The critical current densities versus temperature were calculated from AC susceptibility as well as from the magnetization loops measurements using the Bean's critical state model. The Tl-Re film exhibits the higher critical current in comparison to the rhenium free thallium based film.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Electromagnetic Response in Kinetic Energy Driven Superconductivity: the Meissner Effect
Autorzy:: Krzyzosiak, M.
Lan, Y.
Feng, S.
Jacak, L.
Gonczarek, R.
Tematy:: 74.25.Ha
74.25.N-
74.20.Mn; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1536649.pdf Link otwiera się w nowym oknie
Opis:: Electromagnetic response of cuprate superconductors is studied within the model of kinetic energy driven d-wave superconductivity by analyzing the Meissner effect. The kernel of the linear response function is found and employed to calculate the magnetic field penetration depth and the superfluid density of cuprate superconductors within the specular reflection model for a purely transverse vector potential. It is shown that the magnetic field penetration depth and the superfluid density depend linearly on temperature, except for a strong deviation from the linear characteristics at extremely low temperatures, which is attributed to nonlocal effects. The zero-temperature superfluid density is found to decrease linearly with decreasing doping concentration in the underdoped regime. The problem of gauge invariance in the theoretical description of the electromagnetic response is addressed, and an approximation which does not violate local charge conservation is proposed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

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.
Tematy:: 74.72.Jt
74.25.Sv
74.25.Ha; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1812280.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Studies on Isotope Shift Exponent and Pressure Coefficient for Extended Superconductors within BCS Formalism
Autorzy:: Banerjee, B.
Roy, S.
Tematy:: 74.20.+f
74.25.Bt
74.25.Ha; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1808029.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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