Investigation of Upper Critical Magnetic Field in 1111-Type High-Temperature Iron-Based Superconductor SmFeAsO1-xFx

In this research work, we used a two-band model to study the theoretical analysis of the upper critical magnetic field of a high-temperature iron-based superconductor SmFeAsO1-xFx. The graphs of the high-temperature iron-based superconductor's upper critical magnetic field ((H-c2(||ab)(T) and H-c2(perpendicular to c)(T)) and angular dependence of the field (H-c2(GL)(theta)) versus temperature were effectively plotted. The phase diagrams of the temperature-dependent upper critical magnetic fields versus temperature were suppressed at the transitional temperature and decreased with rising temperature for both directions of the symmetry axis. Additionally, we plotted the phase diagrams and derived the Ginzburg-Landau (GL) parameters ((xi(GL)(T) and lambda(GL)(T)). At the superconducting critical temperature of the superconducting material, these GL parameters diverge at the transitional temperature. Furthermore, a phase diagram of GL characteristic parameter temperature dependence was plotted. By doping fluorine atoms into the parent compound Sm-1111, the transitional temperature of this superconductor material increased, reaching a value of 54 K and above. Finally, our theoretical conclusion is consistent with the previous experimental results.