On the Ginzburg-Landau analysis of the upper critical fieldH_c2in MgB₂

Abstract

We study the temperature dependence of the upper critical field Hc2(T) for superconducting magnesium diboride, MgB2 in the vicinity of Tc using a two-band Ginzburg-Landau (G-L) theory. The temperature dependence of Hc2(T) near Tc exhibits a positive curvature. In addition, the calculated temperature dependence and its higher-order derivatives are also shown to be in good agreement with the experimental data. In analogy with the multi-band character of the Eliashberg microscopic theory, the positive curvature of Hc2(T) is described reasonably by solving the two-band G-L theory.

Enhanced critical parameters of nanocarbon doped MgB2 superconductor

“…From the fitting, we can clearly see that, initially, the behavior of H c2 with T is linear near T c and extends up to a temperature of 10 K and after that it saturates in the range 3-10 K. Below 3 K the H c2 line has negative curvature. The H c2 ͑0͒ for x = 0.15 sample is found to be 21 for the undoped sample and in addition we have applied the same on nanocarbon doped samples and achieved a considerable high value of 300 kOe. The H c2 ͑0͒ values determined for the nanocarbon doped samples are also in confirmation with other reports in which high field measurements by pulsed magnetic field are carried out.…”

“…The GL equation 21 in two band superconductors such as MgB 2 for temperature dependence of H c2 is given by…”

Evidence of multiband behavior in the superconducting alloy Zr0.96V0.04B2Renosto1, Consoline2, Santos3 et al. 2013Phys. Rev. B284251View full textAdd to dashboardCite

“…18,20,21 The deviation is also observed in MgB 2 , which is a superconductor with two bands arising from the holelike boron σ band and the π band. 9,22 Hence, the twoband Eliashberg theory is generally taken as the appropriate description rather than the isotropic single band model.…”

Specific heat jump of two-band superconductor KFe2As2 using Ginzburg-Landau theory

“…We can write GL free energy functional for two order parameter superconductors as follows [20][21][22][23][24][25] …”

“…The four-band Eliashberg model was applied for the study of thermodynamic properties of optimally doped Ba 1−x K x Fe 2 As 2 [19]. The two-band GL theory in application to recently discovered superconductors was developed in [20][21][22][23][24]. The obtained equations were applied to study different physical properties of MgB 2 , nonmagnetic borocarbides, and good agreement with experimental data was achieved.…”