Temat: 74.25.Fy - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Magnetoresistance and Intrinsic Pinning of Vortices in the Untwinned $YBa_2Cu_3O_{7 - δ}$ Single Crystals with Optimal Oxygen Content and a Small Deviation from the Oxygen Stoichiometry
Autorzy:: Vovk, R.
Gvozdikov, V.
Obolenskii, M.
Nazyrov, Z.
Kruglyak, V.
Tematy:: 74.25.Fy
74.25.Qt; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1427580.pdf Link otwiera się w nowym oknie
Opis:: We study the temperature dependence of the in-plane magnetoresistance $ρ_{ab}(T)$ in untwinned $YBa_2Cu_3O_{7 - δ}$ single crystals with the optimal oxygen content and with a small deficit of oxygen atoms at different angles between the external magnetic field 15 kOe and the ab-planes α. We found that at high temperatures in the pseudogap region external magnetic field does not affect the $ρ_{ab}(T)$ but it broadens transitional region $T_{c} - T_{c0}$ from 0.3 K at zero field and α = 0 to approximately 6 K at α = 60° in the field. In case of optimal doping the function $ρ_{ab}(T)$ display a 3D to 2D dimensional crossover when temperature decreases from $T_{c}$ to $T_{c0}$ and scaling near the $T_{c0}$ which we relate to the flux-flow and vortex-lattice melting. In the underdoped sample the vortices are effectively pinned by the random oxygen vacancies and the function $ρ_{ab}(T)$ in transitional region has smooth tails without any traces of crossover and scaling.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 2.

Tytuł:: Compression Changes in Electrical Resistance and Critical Temperature of $Nb_{1-x}Se_2Sn_x$ Single Crystals
Autorzy:: Obolenskiy, M.
Zavgorodniy, A.
Vovk, R.
Nazyrov, Z.
Goulatis, I.
Januszczyk, M.
Latosińska, J.
Tematy:: 74.25.Fy
74.62.Fj; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1419810.pdf Link otwiera się w nowym oknie
Opis:: In this work we investigate the influence of hydrostatic pressure (up to 12 kbar) on the critical parameters of $Nb_{1-x}Se_2Sn_x$ (x=0.1 and x=0.15) single crystals. It is shown that a change in the density of states at the Fermi level brings the main contribution to the increase in $T_{c}$ under pressure. Under the effect of hydrostatic pressure, the phonon spectrum is shifted to higher frequencies (narrowed). The estimated Debye temperature is consistent with those obtained from the heat capacity measurements in $NbSe_2$ single crystals. It is shown that upon increasing hydrostatic pressure the mean free path increases and $Nb_{1-x}Se_2Sn_x$ should be considered as the pure limit in the Ginzburg-Landau theory.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 3.

Tytuł:: Van Hove Singularity and Superconductivity in Disordered Sr$\text{}_{2}$RuO$\text{}_{4}$
Autorzy:: Litak, G.
Annett, J. F.
Györffy, B. L.
Tematy:: 74.62.Dh
74.25.Dw
74.25.Fy; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2012935.pdf Link otwiera się w nowym oknie
Opis:: On the basis of a simple model we analyse the influence of disorder on critical temperature T$\text{}_{c}$ in p-wave superconductors. The disorder is treated by means of the coherent potential approximation and we focus our attention on the effect of a van Hove singularity near Fermi energy E$\text{}_{F}$. For the appropriate values of its parameters our model reproduces the experimentally found behaviour of Sr$\text{}_{2}$ RuO$\text{}_{4}$.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 4.

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

Artykuł

na półce

Skocz do pozycji: 5.

Tytuł:: Phase-Slip Processes in Superconducting Films: AC Josephson Effect and New Phase Transition
Autorzy:: Dmitriev, V.
Zolochevskii, I.
Bezuglyi, E.
Kondrashev, D.
Tematy:: 74.25.Fy
74.25.Nf
74.50.+r; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1812339.pdf Link otwiera się w nowym oknie
Opis:: The resistive direct current state in wide thin superconducting films as the phase transition from superconducting to normal state is investigated in the absence of external magnetic field. We showed that the states of a wide film with increasing transport current appear in the following order: the superconducting state; the resistive vortex state; the critical state; the new vortex-free resistive state with phase-slip lines; the normal state. We detected the Shapiro current steps on the current-voltage characteristic of the wide film, which arise due to interaction of intrinsic Josephson radiation of phase-slip lines with external microwave irradiation.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 6.

Tytuł:: Thermoelectric Power of $MgB_2$ Single Crystals Doped with Holes and Electrons
Autorzy:: Oganisian, K.
Rogacki, K.
Sulkowski, C.
Zhigadlo, N.
Katrych, S.
Karpinski, J.
Tematy:: 74.25.Fy
74.70.Ad
74.62.Dh; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1812320.pdf Link otwiera się w nowym oknie
Opis:: The thermoelectric power of $MgB_2$ single crystals, non-substituted, single-substituted with C, and co-substituted with C and Li, was investigated in the temperature range from 10 to 300 K. Both the in-plane $(S_ab)$ and the out-of-plane $(S_c)$ thermoelectric powers are positive for non-substituted crystals and both $S_{ab}$ and $S_c$ change a sign for crystals doped with electrons when C is substituted for B in the amount larger than 6 at.%. The substitution of C, which supplies electrons mainly into the σ band, reduces the thermoelectric power anisotropy, most likely by increasing the interband scattering. When Li is additionally co-substituted for Mg, $S_ab$ remains unchanged but $S_c$ increases substantially. The Li substitution donates holes into the π band rather than into the σ band and in this way modifies the π band properties, including the possible increase in the intraband scattering.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 7.

Tytuł:: Properties of Normal and Superconducting States of Differently Doped REBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-x}$
Autorzy:: Sułkowski, C.
Tematy:: 74.72.-h
74.25.Fy; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1933589.pdf Link otwiera się w nowym oknie
Opis:: Temperature dependence of resitivity, ρ(T), thermopower, S$\text{}_{300}$, superconducting transition temperature, T$\text{}_{c}$, and lower critical field, Η$\text{}_{c1}$(0), of differently doped REBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-x}$ ceramics have been measured. The hole doping of the CuO$\text{}_{2}$ plane is determined by the T$\text{}_{c}$, the oxygen concentration and/or the value of the thermopower. The temperature dependence of the resistivity above 200 K and the values of the lower critical field H$\text{}_{c1}$(0) show clear dependence on the hole concentration. Below 200 K, in contrast to simple metals, the resitivity of all samples decreases faster than linearly with the decreasing temperature. Classical electron-phonon scattering mechanism is not appropriate to describe the ρ(T) curves of REBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-x}$ compounds. Some observed features of the ρ(T) dependence are predicted by mean field phase diagram for the CuO$\text{}_{2}$ plane.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 8.

Tytuł:: Asymmetric Tunneling Conductance in Doped Antiferromagnets
Autorzy:: Maciąg, A.
Wróbel, P.
Tematy:: 71.10.Fd
74.20.Mn
74.25.Fy; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2046776.pdf Link otwiera się w nowym oknie
Opis:: We calculate the tunneling conductance in the framework of the spin polaron model, which is an effective model for the t-J model, in the limit where at least short-range antiferromagnetic correlations exist. We show that both in the normal state and in the superconducting state the asymmetry of tunneling conductance is present. This fact is the implication of the particle-hole asymmetry of the spin polaron Hamiltonian in the limit of low density of spin polarons which are quasiparticles emerging in a hole doped antiferromagnet. Experimental evidence of analogous asymmetric tunneling conductance was found in the tunneling spectroscopy measurements of high T$\text{}_{c}$ superconductors.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 9.

Tytuł:: Negative Magnetoresistance in the Variable-Range-Hopping Transport of Strongly Underdoped La$\text{}_{2-x}$Sr$\text{}_{x}$CuO$\text{}_{4}$
Autorzy:: Malinowski, A.
Cieplak, M. Z.
Berkowski, M.
Guha, S.
Tematy:: 74.72.-h
74.25.Fy
73.43.Qt; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2046779.pdf Link otwiera się w nowym oknie
Opis:: The in-plane transport of strongly underdoped La$\text{}_{2-x}$Sr$\text{}_{x}$CuO$\text{}_{4}$ films was examined in the magnetic fields up to 14 T and in temperatures down to 1.6 K. While at high temperatures the samples display metallic-like resistivity, the low-T transport is governed by variable-range-hopping mechanism. Careful analysis shows that the temperature dependence of pre-exponential factor in Mott's variable-range-hopping law may not be neglected and that the density of states at the Fermi level can be effectively expressed as g(E-E$\text{}_{F}$)=N$\text{}_{0}$ (E-E$\text{}_{F}$)$\text{}^{p}$, with a small exponent p of the order of 0.1. In the magnetic field parallel to CuO$\text{}_{2}$ planes one of the variable-range-hopping parameter,ρ$\text{}_{0}$, increases by about 20-25%, while the other one, T$\text{}_{0}$, decreases by about 10-15%, resulting in the decrease in total resistivity. This effect may be related to the decrease of the tunneling barrier between different antiferromagnetic clusters in the presence of magnetic field.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 10.

Tytuł:: Metal-Insulator Transition in Zinc-Doped LaSrCuO
Autorzy:: Malinowski, A.
Cieplak, M. Z.
Berkowski, M.
Plesiewicz, W.
Skośkiewicz, T.
Tematy:: 74.72.-h
71.30.+h
74.25.Fy; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2046782.pdf Link otwiera się w nowym oknie
Opis:: The magnetotransport in the vicinity of the metal-insulator transition in La$\text{}_{1.85}$Sr$\text{}_{0.15}$Cu$\text{}_{x}$Zn$\text{}_{1-x}$O$\text{}_{4}$ is studied in the mK temperature range. Both longitudinal and transverse magnetoresistance are negative indicating the importance of spin effects. The magnitude of transverse magnetoresistance is larger than the magnitude of longitudinal magnetoresistance, indicating the absence of positive orbital magnetoresistance, in sharp contrast to strongly underdoped La$\text{}_{2-x}$Sr$\text{}_{x}$CuO$\text{}_{4}$. Both transverse and longitudinal magnetoresistance are proportional to the relative change of zero-field conductivity. This suggests that low-temperature localization of carriers may originate in the spin-disorder scattering on the spin droplets around Zn-impurities.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Informacja

Wyszukujesz frazę "74.25.Fy" wg kryterium: Temat