The purpose of this research is to study the upper critical field (H c2 ) of two-band superconductors by two-band Ginzburg -Landau approach. The analytical formula of H c2 included anisotropy of order parameter and anisotropy of effective-mass are found . The parameters of the upper critical field in ab-plane( but it has an unusual temperature dependence. Askerzade [10] study H c1 (T) and H c2 (T) for MgB 2 and nonmagnetic borocarbides by using the isotropy two-band Ginzberg-Landau model. He shows the complicate formula of critical magnetic field. In the H c2 consideration, his formula is less fit to experimental data than Drechsler 's [11]. In the recent work of Dao and Zhitomirsky [12] ,they study the effect of angular and temperature on upper critical field of MgB 2 determined with the anisotropy two-band Ginzberg-Landau theory. They found that the temperature variation of the ratio of two gaps is responsible for the upward temperature dependence of in-plane H c2 as well as for the deviation of its out-of-plane behavior from the standard angular dependence.In this paper, we study the upper critical magnetic field( 2 c H ) of anisotropy two-band swave superconductors by Ginzburg-Landau theory . We can find the formula of H c2 included anisotropy of order parameter and anisotropy of effective-mass . The upper critical field in abplane( ab c

The upper and lower critical field, and the critical field ratio of an anisotropic two-band magnetic superconductors in Ginzburg-Landau(GL) scenery is derived analytically. The temperature-dependent on the upper critical field is investigated and applied to Fe-based superconductors. We find that the very high value of zero-temperature upper critical field in Febased superconductors can be found in the negative differential susceptibility region. The temperature-dependent upper critical field is presented in two formulas as in the empirical view and in the GL two-band view that agrees with the experiment results.

The upper critical field, the lower critical field and the critical magnetic field ratio of anisotropic magnetic superconductors are calculated by Ginzburg-Landau theory analytically. The effect of the GinzburgLandau parameter( 0 κ ), magnetic susceptibility( χ ) and magnetic-toanisotropic parameter ratio(θ ) on the critical field ratio are considered. We find that the value of critical magnetic field ratio with 0 < χ , higher 0 κ ,and higher θ case are shown the higher value. And, the diamagnetic superconductors with highly anisotropic and the ferromagnetic superconductors are shown the highest and the lowest, respectively.

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