A. ChangjanP. UdomsamuthirunSrinakharinwirot UniversityThailand Center of Excellence in PhysicsMahidol University2018-05-032018-05-032011-07-01Solid State Communications. Vol.151, No.14-15 (2011), 988-992003810982-s2.0-79958261802https://repository.li.mahidol.ac.th/handle/20.500.14594/11709The upper and lower critical fields, and the critical field ratio of an anisotropic two-band magnetic superconductor in the GinzburgLandau (GL) scenario is derived analytically. The temperature-dependent upper critical field is investigated and applied to Fe-based superconductors. We find that a very high value of zero-temperature upper critical field in Fe-based superconductors can be found in the negative differential susceptibility region. The temperature-dependent upper critical field is presented in two formulas, in the empirical view and in the GL two-band view, which agrees with the experimental results. © 2011 Elsevier Ltd. All rights reserved.Mahidol UniversityChemistryMaterials SciencePhysics and AstronomyArticleSCOPUS10.1016/j.ssc.2011.04.032