Temperature Dependence of the Ginzburg-Landau Coefficient in Type-I Superconductors

1965 ◽  
Vol 137 (6A) ◽  
pp. A1816-A1821 ◽  
Author(s):  
Arthur Paskin ◽  
Myron Strongin ◽  
Paul P. Craig ◽  
Donald G. Schweitzer
1997 ◽  
Vol 499 ◽  
Author(s):  
S. Guha ◽  
Q. Cai ◽  
M. Chandrasekhar ◽  
H. R. Chandrasekhar ◽  
Hyunjung Kim ◽  
...  

ABSTRACTWe have studied the pressure dependence of the type-I and type-II transitions in (GaAs)m/(AlAs)m superlattices by photoluminescence (PL) spectroscopy. From the study of PL linewidths of the type-I exciton as a function of pressure and temperature, we determine the intervalley deformation potential. Beyond the type-I and type-II crossover, the PL linewidth increases both as a function of pressure and temperature. We find that the electron-phonon deformation potential for Γ-X intervalley scattering varies with temperature.


2004 ◽  
Vol 18 (13) ◽  
pp. 1931-1936 ◽  
Author(s):  
I. N. ASKERZADE

Temperature dependence of the critical current density j c (T) for the superconducting magnesium diboride MgB 2 is studied in the vicinity of T c by using a two-band Ginzburg–Landau (G–L) theory. The result is in good agreement with experimental data for a bulk MgB 2. Comparision of obtained results with single-band GL theory are presented.


Author(s):  
Rami Ahmad El-Nabulsi

Superconductivity is analysed based on the product-like fractal measure approach with fractal dimension α introduced by Li and Ostoja-Starzewski in their attempt to explore anisotropic fractal elastic media. Our study shows the emergence of a massless state at the boundary of the superconductor and the simultaneous occurrence of isothermal and adiabatic processes in the superconductor depending on the position of the electrons. Several physical quantities were found to be position-dependent comparable with those arising in heavy doping and p–n junction. At the boundary of the superconductor, a shrinkage of the magnetic field was observed, leading to a scenario equivalent to the Meissner–Ochsenfeld effect. An enhancement of the London penetration depth is revealed and such an improvement was observed in pnictides at the onset of commensurate spin-density-wave order inside the superconducting phase at zero temperature. The Bardeen–Cooper–Schrieffer theory was also analysed and the appearance of zero-energy states is detected. Nucleation of superconductivity in a bulk was also studied. The system acts as a quantum damped harmonic oscillator and our analysis showed that type-I superconductivity occurs when κ < 2 / ( 1 + α ) , whereas type II occurs for κ > 2 / ( 1 + α ) , where κ is the Ginzburg–Landau parameter. The transition at the passage from the ‘genuine’ to the ‘intermediate’ type-I estimates 0.767767 < α ≤ 1 .


Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1591
Author(s):  
Jennifer Pulsifer ◽  
Edward Laws

Phytoplankton growth rates and zooplankton grazing rates were estimated on 16 occasions over a period of 17 months in University Lake, a highly eutrophic lake on the campus of Louisiana State University. Phytoplankton growth rates and chlorophyll a concentrations averaged 1.0 ± 0.2 d−1 and 240 ± 120 mg m−3, respectively. Chlorophyll a concentrations were at or above the inflection point of the Holling type I curve that described the relationship between zooplankton grazing rates and chlorophyll a concentrations. In most cases, it was necessary to dilute lake water by more than a factor of 4 before zooplankton grazing rates became sensitive to chlorophyll a concentrations. Chlorophyll a concentrations were positively correlated with temperature and were roughly fourfold higher at 30 °C than at 15 °C. An analysis of the temperature dependence of the growth rates and grazing rates in this study and 87 other paired estimates of limnetic phytoplankton growth rates and zooplankton grazing rates revealed virtually identical temperature dependences of growth rates and grazing rates that were very similar to the temperature dependence predicted by the metabolic theory of ecology. Phytoplankton growth rates exceeded zooplankton grazing rates by 0.13 ± 0.05 d−1 at all temperatures over a temperature range of 8.5–31.5 °C. The Q10 for both phytoplankton growth rates and zooplankton grazing rates was 1.5 over that temperature range.


2004 ◽  
Vol 18 (30) ◽  
pp. 1525-1531 ◽  
Author(s):  
I. N. ASKERZADE

Temperature dependence of the upper critical field [Formula: see text] of thin films of two-band superconductors is studied using the two-band Ginzburg–Landau (G–L) theory. The results are shown to be in qualitative agreement with experimental data for the superconducting magnesium diboride MgB 2 films.


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