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Wyświetlanie 1-15 z 18
Tytuł:
Superconductivity in ThIr₂Si₂
Autorzy:
Domieracki, K.
Kaczorowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/1398629.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.-q
74.70.Dd
Opis:
The compound ThIr₂Si₂ crystallizes with a tetragonal crystal structure of the CaBe₂Ge₂-type (space group P4/nmm). Its low-temperature physical properties were investigated by means of magnetization, electrical resistivity, and heat capacity measurements, performed down to 0.35 K. The experiments revealed bulk superconductivity below $T_{c}$ = 2 K. The obtained data indicate that ThIr₂Si₂ is a weakly-coupled type-II BCS superconductor.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 593-596
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the Granularity on the Transversal Resistance in Y_{0.55}Pr_{0.45}Ba_2Cu_3O_{7-δ} Superconductor
Autorzy:
da Luz, M.
dos Santos, C.
Machado, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399293.pdf
Data publikacji:
2013-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.-q
74.25.Fy
74.81.Bd
Opis:
This work reports longitudinal $(R_{XX})$ and transverse $(R_{XY})$ resistance as a function of temperature measured at low magnetic fields for $Y_{0.55}Pr_{0.45}Ba_2Cu_3O_{7-δ}$ polycrystalline sample. It is observed non-zero transverse resistance at zero applied magnetic field below superconducting transition. The comparison between $R_{XX} (T)$ and $R_{XY} (T)$ curves demonstrate unambiguously that the transverse resistance is related to the double resistive superconducting transition in granular superconductors. I-V curves indicate that the transport properties of the investigated sample are in agreement with the predictions of the two-fluid model.
Źródło:
Acta Physica Polonica A; 2013, 124, 4; 702-705
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Pseudogap Phenomenon in High-T$\text{}_{c}$ Superconductors
Autorzy:
Ranninger, J.
Romano, A.
Powiązania:
https://bibliotekanauki.pl/articles/2011238.pdf
Data publikacji:
2000-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.25.-q
74.25.Jb
Opis:
We review the possible mechanisms leading up to the phenomenon of a pseudogap which characterizes the normal-state properties of high-T$\text{}_{c}$ superconductors. We suggest that this pseudogap is not due to superconducting phase fluctuations and hence is not related to a crossover between a BCS state of Cooper pairs and a Bose-Einstein condensation of local pairs. We rather argue that it is due to uncorrelated pairing which is already manifest in the local electronic structure and accessible by photoemission and tunneling experiments.
Źródło:
Acta Physica Polonica A; 2000, 97, 1; 157-164
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the current flow in superconductors: universal trends and holographic analysis
Autorzy:
Rogatko, M.
Wysokiński, K.
Powiązania:
https://bibliotekanauki.pl/articles/1048283.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.-q
74.25.Sv
11.25.Tq
Opis:
The superconducting state can be destroyed by the increase of temperature, magnetic field or current flow beyond their critical values. The critical current I_{c} is of special interest as most of the practical applications of superconductors crucially depend on its limiting value. Recent analysis of experimental data in many families of type I and type II superconductors have discovered an interesting universal relation between critical current density j_{c}, the critical magnetic field H_{c} and the penetration depth λ. For type II superconductors the role of the thermodynamic critical field H_{c} is played by the lower critical field H_{c1} and ratio between the relevant dimension of the system d with respect to the penetration depth matters. Thus the effective dimensionality of the system is important and rules the system behaviour. It turns out that the holographic analogy provides an interesting justification of the above findings. We have calculated the temperature dependence of the critical current in the strongly coupled holographic superconductors with the current flow. It has been found that, independently of the symmetry of the order parameter, the critical current depends on temperature in 2d systems as I_{c} ∝ (T_{c}-T)^{3/2} and agrees with that observed in thin films (d < λ). Similar calculations for 3d systems (d > λ) reveal linear T-dependence I_{c} ∝ (T_{c}-T).
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 376-379
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Scattering Study of (Sr,Ca)$\text{}_{10}$Cu$\text{}_{17}$O$\text{}_{29}$ Single Crystals
Autorzy:
Strzeszewski, J.
Szymczak, H.
Leonyuk, L.
Szymczak, R.
Powiązania:
https://bibliotekanauki.pl/articles/2014363.pdf
Data publikacji:
2000-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Hv
74.25.Gz
74.25.-q
Opis:
Polarized Raman spectra of high temperature superconducting single crystals of A$\text{}_{10}$Cu$\text{}_{17}$O$\text{}_{29}$ (A$\text{}_{10}$=Ca$\text{}_{4.7}$Sr$\text{}_{4.1}$Bi$\text{}_{0.3}$) were studied in various scattering configurations in the range of 40-700cm$\text{}^{-1}$. In very distinctive spectra there were found over 20 peaks. It was observed that the flat continuum of electronic excitations in the normal state was redistributed below the critical temperature. The frequency dependent redistribution is consistent with the value of energy gap estimated using tunnelling spectroscopy techniques.
Źródło:
Acta Physica Polonica A; 2000, 98, 4; 429-439
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity in $Lu_xZr_{1-x}B_{12}$ Dodecaborides with Cage-Glass Crystal Structure
Autorzy:
Sluchanko, N.
Azarevich, A.
Bogach, A.
Gavrilkin, S.
Glushkov, V.
Demishev, S.
Mitsen, K.
Shitsevalova, N.
Filippov, V.
Gabani, S.
Flachbart, K.
Powiązania:
https://bibliotekanauki.pl/articles/1398292.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.-q
74.62.Bf
74.70.Ad
Opis:
We probed the evolution of the superconducting transition temperature $T_c$ and the normal state parameters of $Lu_xZr_{1-x}B_{12}$ solid solutions employing resistivity, heat capacity and magnetization measurements. In these studies of high-quality single crystals it was found that there are two types of samples with different magnetic characteristics. An unusually strong suppression of superconductivity in $Lu_xZr_{1-x}B_{12}$ with a rate $dT_c/dx=0.21 K/at.%$ of Lu was observed previously on the first "magnetic" set of crystals, and it was argued to be caused by the emergence of static spin polarization in the vicinity of non-magnetic lutetium ions. On the contrary, the second (current) set of "nonmagnetic" crystals demonstrates a conventional $T_c(x)$ dependence with a rate $dT_c/dx=0.12 K/at.%$ of Lu which is typical for BCS-type superconductors doped by nonmagnetic impurities. The reason for this difference is yet unclear. Moreover, the H-T phase diagram of the superconducting state of $Lu_xZr_{1-x}B_{12}$ (0 ≤ x ≤ 1) solid solutions has been deduced from magnetization measurements.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1036-1038
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrathin Niobium in the Si/Nb/Si Trilayers
Autorzy:
Zaytseva, I.
Abal'oshev, O.
Dłużewski, P.
Minikayev, R.
Cieplak, Marta
Zhu, L.
Chien, C.
Powiązania:
https://bibliotekanauki.pl/articles/1374193.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
74.70.Ad
74.25.-q
Opis:
We study magnetotransport properties of the Si/Nb/Si trilayers, in which the thickness of niobium, d, changes from 1.1 nm to 50 nm, while the thickness of Si is fixed at 10 nm. The niobium films are amorphous for d < 4 nm, while in thicker films the alligned polycrystalline grains are formed. We observe that the Hall coefficient changes sign into negative in the films with d < 1.6 nm. We also find that in the ultrathin films the magnetic field induces a transition from the superconducting into a metallic phase with the resistance smaller than the normal-state resistance.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-140-A-144
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coherence Lengths for Superconductivity in the Two-Orbital Negative-U Hubbard Model
Autorzy:
Litak, G.
Örd, T.
Rägo, K.
Vargunin, A.
Powiązania:
https://bibliotekanauki.pl/articles/1431204.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.20.Mn
74.25.-q
Opis:
We study the peculiarities of coherency in the superconductivity of two-orbital system. The superconducting phase transition is caused here by the on-site intra-orbital attractions (negative-U Hubbard model) and inter-orbital pair-transfer interaction. The dependencies of critical and non-critical correlation lengths on interaction channels and band fillings are analyzed.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 747-751
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity in Anderson Lattice Model
Autorzy:
Romano, A.
Noce, C.
Micnas, R.
Powiązania:
https://bibliotekanauki.pl/articles/1955827.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.70.Tx
74.25.-q
Opis:
We study the superconducting instabilities generated by the inclusion in the Anderson lattice model of a density-density attractive potential between correlated electrons on nearest-neighbouring sites. Using a description of the normal phase based on a perturbative expansion around the atomic limit, we treat the attractive potential in the broken-symmetry Hartree-Fock scheme and analyze which of the possible symmetries of the superconducting order parameter leads to the highest possible transition temperature in the case of a two-dimensional square lattice. For values of the on-site f-repulsion large compared to the hopping amplitude, a suppression of any possible superconducting phase occurs, regardless of the symmetry of the order parameter.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 381-385
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Anisotropy of Fe Films in MgO/Cu(t$\text{}_{Cu}$)/Fe/Cu Systems
Autorzy:
Baszyński, J.
Toliński, T.
Powiązania:
https://bibliotekanauki.pl/articles/1955437.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
73.20.Mf
74.25.-q
Opis:
Ferromagnetic resonance was employed to study the magnetic anisotropy of the Fe thin film in the MgO/Cu(t$\text{}_{Cu}$)/Fe/Cu system. The Fe film showed strong fourfold cubic anisotropy (H_{K$\text{}_{1}}$ = 2K$\text{}_{1}$/M = 46.15 kA/m) for t$\text{}_{Fe}$ = 23 nm and t$\text{}_{Cu}$ = 0. The spread of the crystallographic axes Δβ = 0.5° was evaluated from the angular dependence of the resonance line width ΔH$\text{}_{pp}$ (4.4 < ΔH$\text{}_{pp}$ < 6.4 kA/m). Such a small mosaicity confirmed the epitaxial growth of the Fe film. The Cu buffer layer destroys this growth of the Fe film which showed only a weak anisotropy.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 245-248
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fano Resonance in a Coupled Electron-Phonon System
Autorzy:
Falkovsky, L. A.
Klama, S.
Powiązania:
https://bibliotekanauki.pl/articles/1955509.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
73.20.Mf
74.25.-q
Opis:
Raman light scattering with excitation of electron-hole continuum and a phonon is investigated theoretically. The effect of a surface and screening of the electron-photon coupling and of the deformation potential as a result of the Coulomb interaction of the electrons is taken into account. The parameters of the 340 cm$\text{}^{-1}$ resonance line in superconducting YBaCuO are estimated by comparing with experimental data.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 347-350
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
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:
Non-Fermi Liquid States of a General Model of Copper-Oxide Metals
Autorzy:
Varma, C. M.
Powiązania:
https://bibliotekanauki.pl/articles/1953178.pdf
Data publikacji:
1997-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Hf
74.72.-h
74.20.Mn
74.25.-q
Opis:
A summary is given of the minimum requirements posed by experimental results on a theory of copper-oxide metals and of the recent solution of a model of copper-oxygen bonding and anti-bonding bands with the most general two-body interactions allowable by symmetry which satisfies these requirements. Several experiments were proposed to test the theory.
Źródło:
Acta Physica Polonica A; 1997, 91, 1; 191-201
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes in YBCO Single Grain Bulk Superconductor Exposed to Air Moisture
Autorzy:
Piovarči, S.
Antal, V.
Kaňuchová, M.
Radušovská, M.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1202072.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.25.-q
68.43.-h
68.37.-d
Opis:
Changes in bulk single grain YBCO superconductor at exposition to air were studied. The increase of the sample weight caused by reaction with air moisture was observed by weighing the samples over two months period. Thermal analyses and mass spectrometry of the exposed samples has shown evolution of water and oxygen during sample heating. Observation with scanning electron microscope confirmed the formation of some nanosize phases at the inner sample surfaces. XPS spectra done on the freshly cleaved and on the air exposed (001) surfaces confirmed changes in Ba and Cu bonds. Observed structural changes did not caused systematic changes in measured trapped field.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 364-365
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of Fast Neutron Irradiation on the Magnetostriction of Ceramic YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ Sample
Autorzy:
Nabiałek, A.
Vasiliev, S.
Pytel, B.
Chabanenko, V. V.
Piechota, S.
Powiązania:
https://bibliotekanauki.pl/articles/2041474.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Qt
74.72.Bk
75.80.+q
Opis:
We investigated the magnetostriction of ceramic YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ sample both before and after fast neutron irradiation with the fluency of 7.55×10$\text{}^{17}$ n/cm$\text{}^{2}$ and energy of above 0.5 MeV. We have found that after irradiation the widths of both transverse and longitudinal magnetostriction hysteresis loops at a given temperature and at a given external magnetic field increased several times. At 4.2 K and in 10 tesla the widths of the magnetostriction hysteresis loop of the irradiated sample are of an order of 10$\text{}^{-5}$. The results can be understood in the framework of the model of the magnetostriction induced by the pinning forces, assuming the stress in the sample to be induced mainly by the intragrain screening currents.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 739-744
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 18

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