Investigation of upper critical magnetic field (HC2 (T)) of NdFeAsO1-xFx by Ginzburg-Landau two-band model at x = 0.2

This research work deals with the theoretical investigation of the temperature dependence of upper critical magnetic field (H_C2 (T)) in iron-based superconductor NdFeAsO_1-xF_x by engaging the Ginzburg–Landau (GL) two-band model. Phase diagrams of the parallel upper critical magnetic field, perpendicular upper critical magnetic field, and angle dependence of the upper critical magnetic field versus the temperature of superconductor NdFeAsO_1-xF_x are plotted successfully. As temperature rises, the two oriented upper critical magnetic fields progressively decrease and vanish at the superconducting transitional temperature of NdFeAsO_1-xF_x. Also, the GL parameters coherence length and penetration depth are calculated and expressed graphically. The aforementioned GL parameters increase with increasing temperature and diverge at the superconducting transitional temperature (47 K) of the superconducting material. Likewise, the phase diagram of the GL characteristic parameter versus temperature is plotted and it decreases with increasing temperature and vanished at its transitional temperature.