Angular effects on upper critical field in LiFeAs using two-band Ginzburg-Landau theory

The influence of angular effects on the upper critical field is studied by using generalized two-band Ginzburg-Landau (GL) theory. It is shown that such a model is in better agreement with known experimental data for the new superconductor LiFeAs. The deviation from single-band GL theory is maximum at temperatures close to T-c. Different anisotropy of different bands leads to an increase of the anisotropy parameter of the upper critical field gamma(T) with increase of temperature.