A study was made of the temperature dependence of the upper critical field HC2(T) in the vicinity of TC by using a 2-band Ginzburg-Landau theory. The temperature dependence of HC2(T) near to TC exhibited a positive curvature. In addition, the calculated temperature dependence and its higher-order derivatives were also shown to be in good agreement with the experimental data. In analogy with the multi-band character of theEliashberg microscopic theory, the positive curvature of HC2(T) was described reasonably by solving the 2-band Ginzburg-Landau theory.

On the Ginzburg-Landau Analysis of the Upper Critical Field HC2 in MgB2. I.N.Askerzade, A.Gencer, N.Güçlü: Superconductor Science and Technology, 2002, 15, L13-6