Ginzburg–Landau Theory for Two-Band Isotropic s-Wave Superconductors

2003 ◽  
Vol 17 (16) ◽  
pp. 3001-3020 ◽  
Author(s):  
I. N. Askerzade
Keyword(s):  
Magnetic Field ◽  
Critical Field ◽  
Landau Theory ◽  
Upper Critical Field ◽  
Single Band ◽  
S Wave ◽  
Ginzburg Landau ◽  
Surface Magnetic Field ◽  
Specific Heat Jump ◽  
Gl Theory

Temperature dependence of the upper critical field Hc2(T), lower critical field Hc1(T) and thermodynamic magnetic field Hcm(T) are studied in the vicinity of Tc using a two-band Ginzburg–Landau (GL) theory. The results are shown to be in a good agreement with experimental data for the superconducting magnesium diboride (MgB2) and non-magnetic borocarbides LuNi 2 B 2 C ( YNi 2 B 2 C ). In addition, two-band GL theory was applied for the calculation of specific heat jump, which is smaller than in single-band GL theory. Peculiarities of Little–Parks effect in two-band GL theory are studied also. It is shown that the quantization of the magnetic flux and the relation between surface magnetic field Hc3(T) and upper critical field Hc2(T) are the same as in single band GL theory.

Mean-field analysis on the magnetic properties of non-centrosymmetric superconductor LaNiC2

2018 ◽  
Vol 96 (2) ◽  
pp. 189-193
Author(s):  
Jia-Li Zhang
Keyword(s):  
Critical Field ◽  
Landau Theory ◽  
Theoretical Calculations ◽  
Mean Field ◽  
Upper Critical Field ◽  
Field Analysis ◽  
S Wave ◽  
Wave State ◽  
Ginzburg Landau ◽  
Upward Curvature

Based on two-band isotropic Ginzburg–Landau theory, we study the temperature dependence of upper critical field and London penetration depth for non-centrosymmetric superconductor LaNiC2. All the theoretical calculations fit the experimental data very well, especially the upward curvature of upper critical field near the critical temperature. Our results thus indicate that the two-gap scenario is better to account for the superconductivity of LaNiC2, and the Cooper pairs of this superconductor are in the conventional s-wave state.

Ginzburg–Landau theory of the Abrikosov vortex state near the upper critical field

1982 ◽  
Vol 60 (3) ◽  
pp. 299-303 ◽  
Author(s):  
A. E. Jacobs
Keyword(s):  
Critical Field ◽  
Landau Theory ◽  
Upper Critical Field ◽  
Vortex State ◽  
Quantization Condition ◽  
Abrikosov Vortex ◽  
Ginzburg Landau ◽  
Type Ii Superconductors ◽  
Flux Quantization ◽  
The Magnetic Field

A method which preserves the flux-quantization condition in all orders of perturbation theory is applied to the Ginzburg–Landau theory of type-II superconductors near the upper critical field. Expansions are obtained for the order parameter, the magnetic field, and the free energy; previous results are verified and extended to one higher order in Hc2 – Ha.

ON THE SECOND CRITICAL FIELD FOR A GINZBURG–LANDAU MODEL WITH FERROMAGNETIC INTERACTIONS

2004 ◽  
Vol 16 (02) ◽  
pp. 147-174 ◽  
Author(s):  
STAN ALAMA ◽  
LIA BRONSARD
Keyword(s):  
Magnetic Field ◽  
Critical Field ◽  
Order Parameter ◽  
Upper Critical Field ◽  
Average Energy ◽  
Spin Coupling ◽  
P Wave ◽  
Ginzburg Landau ◽  
Landau Model ◽  
Second Critical Field

We consider a two-dimensional Ginzburg–Landau model for superconductors which exhibit ferromagnetic ordering in the superconducting phase, introduced by physicists to describe unconventional p-wave superconductors. In this model the magnetic field is directly coupled to a vector-valued order parameter in the energy functional. We show that one effect of spin coupling is to increase the second critical field Hc2, the value of the applied magnetic field at which superconductivity is lost in the bulk. Indeed, when the spin coupling is strong we show that the upper critical field is no longer present, confirming predictions in the physics literature. We treat the energy density as a measure, and show that the order parameter converges (as the Ginzburg–Landau parameter κ→∞) in an average sense to a constant determined by the average energy.

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