Temat: 74.25.-q - Prolib Integro

Skocz do pozycji: 1.

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.
Tematy:: 74.25.-q
74.25.Fy
74.81.Bd; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1399293.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

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.
Tematy:: 78.30.Hv
74.25.Gz
74.25.-q; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2014363.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

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.
Tematy:: 74.25.-q
74.62.Bf
74.70.Ad; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1398292.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

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.
Tematy:: 74.78.-w
74.70.Ad
74.25.-q; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1374193.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Superconductivity in ThIr₂Si₂
Autorzy:: Domieracki, K.
Kaczorowski, D.
Tematy:: 74.25.-q
74.70.Dd; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1398629.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: The Pseudogap Phenomenon in High-T$\text{}_{c}$ Superconductors
Autorzy:: Ranninger, J.
Romano, A.
Tematy:: 74.20.-z
74.25.-q
74.25.Jb; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2011238.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: On the current flow in superconductors: universal trends and holographic analysis
Autorzy:: Rogatko, M.
Wysokiński, K.
Tematy:: 74.25.-q
74.25.Sv
11.25.Tq; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1048283.pdf Link otwiera się w nowym oknie
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).
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Non-Fermi Liquid States of a General Model of Copper-Oxide Metals
Autorzy:: Varma, C. M.
Tematy:: 71.10.Hf
74.72.-h
74.20.Mn
74.25.-q; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1953178.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Coherence Lengths for Superconductivity in the Two-Orbital Negative-U Hubbard Model
Autorzy:: Litak, G.
Örd, T.
Rägo, K.
Vargunin, A.
Tematy:: 74.20.-z
74.20.Mn
74.25.-q; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1431204.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Superconductivity in Anderson Lattice Model
Autorzy:: Romano, A.
Noce, C.
Micnas, R.
Tematy:: 74.72.-h
74.70.Tx
74.25.-q; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1955827.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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