Renormalization group calculation of the critical temperature dependence on longitudinal magnetic field for a disordered superconductor model

1990 ◽  
Vol 78 (3) ◽  
pp. 485-487 ◽  
Author(s):  
Biao Xing ◽  
K. L. Yao
2009 ◽  
Vol 152-153 ◽  
pp. 462-465 ◽  
Author(s):  
Maxim Avdeev ◽  
Mansur G. Khusainov ◽  
Yurii N. Proshin ◽  
Sergey Tsarevskii

The proximity effect of the ferromagnetic metal/superconductor (FM/S) bilayers in а external longitudinal magnetic field is considered in the dirty limit. The critical temperature and the superconducting current distribution versus applied magnetic field’s magnitude, film’s thicknesses and a transparency of the contact is calculated, with taking into account аn umklapp processes possibility on the interface of the FM/S contact. It is shown that superconducting current is strictly inhomogeneous and asymmetrical. It is shown also that the current inhomogeneity depends heavily from the FM/S interface transparency.


1996 ◽  
Vol 10 (27) ◽  
pp. 1349-1353
Author(s):  
I. POP ◽  
L. HOMORODEAN ◽  
I. BURDA ◽  
M. ANDRECUT

A high-Tc YBa 1.5 Ca 0.5 Cu 3 O 6+δ superconductor was synthesized, with the critical temperature Tc=84.9 K. The crystalline structure is orthorhombic with the lattice parameters a=3.8665 Å, b=3.9217 Å and c=11.7652 Å, characteristic for the 123 superconductors. The diamagnetic transition in the temperature dependence of the magnetic susceptibility strongly depends on the recycling of the samples and the onset of superconductibility is depressed by the magnetic field intensity.


2011 ◽  
Vol 25 (27) ◽  
pp. 2131-2136 ◽  
Author(s):  
R. V. VOVK ◽  
M. A. OBOLENSKII ◽  
A. A. ZAVGORODNIY ◽  
Z. F. NAZYROV ◽  
I. L. GOULATIS ◽  
...  

In this work we study the influence of the constant magnetic field up to 14 kOe to the temperature dependence of the electrical conductivity in the ab-plane of aluminium doped YBa 2 Cu 3 O 7-δ single crystals with an unidirectional twin boundaries system. The temperature dependence of the excess para-conductivity is interpreted within the Aslamazov–Larkin theoretical model of the fluctuation conductivity. It was shown that the lack of fan-shaped expansion of the resistive transitions in the magnetic field in these samples may be due to the lack of the non-pinning vortex liquid phase.


2019 ◽  
Vol 2019 (2) ◽  
pp. 19-21
Author(s):  
A.D. Razmyshlyaev ◽  
◽  
M.V. Ageeva ◽  
E.V. Lavrova ◽  
◽  
...  

Author(s):  
G. Gulyamov ◽  
U. I. Erkaboev ◽  
A. G. Gulyamov

The article considers the oscillations of interband magneto-optical absorption in semiconductors with the Kane dispersion law. We have compared the changes in oscillations of the joint density of states with respect to the photon energy for different Landau levels in parabolic and non-parabolic zones. An analytical expression is obtained for the oscillation of the combined density of states in narrow-gap semiconductors. We have calculated the dependence of the maximum photon energy on the magnetic field at different temperatures. A theoretical study of the band structure showed that the magnetoabsorption oscillations decrease with an increase in temperature, and the photon energies nonlinearly depend on a strong magnetic field. The article proposes a simple method for calculating the oscillation of joint density of states in a quantizing magnetic field with the non-quadratic dispersion law. The temperature dependence of the oscillations joint density of states in semiconductors with non-parabolic dispersion law is obtained. Moreover, the article studies the temperature dependence of the band gap in a strong magnetic field with the non-quadratic dispersion law. The method is applied to the research of the magnetic absorption in narrow-gap semiconductors with nonparabolic dispersion law. It is shown that as the temperature increases, Landau levels are washed away due to thermal broadening and density of states turns into a density of states without a magnetic field. Using the mathematical model, the temperature dependence of the density distribution of energy states in strong magnetic fields is considered. It is shown that the continuous spectrum of the density of states, measured at the temperature of liquid nitrogen, at low temperatures turns into discrete Landau levels. Mathematical modeling of processes using experimental values of the continuous spectrum of the density of states makes it possible to calculate discrete Landau levels. We have created the three-dimensional fan chart of magneto optical oscillations of semiconductors with considering for the joint density of energy states. For a nonquadratic dispersion law, the maximum frequency of the absorbed light and the width of the forbidden band are shown to depend nonlinearly on the magnetic field. Modeling the temperature  dependence allowed us to determine the Landau levels in semiconductors in a wide temperature spectrum. Using the proposed model, the experimental results obtained for narrow-gap semiconductors are analyzed. The theoretical results are compared with experimental results.


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