Tsega, Moges2018-07-022023-11-092018-07-022023-11-092005-07http://10.90.10.223:4000/handle/123456789/5168The co- existence of superconductive and magnetic properties of Yi - xPrxB(i2Cu307-s has been investigated. The suppression of Tc by the Pr concentration can be described by the Abrikosov-Gorkov pair-breaking like relation , and hybridization between Pr 4f states and conduction bands may play an important role in the suppression of Tc . We have determined the dependency of Tc on the impurity concentration. Superconductivity vanishes at a certain critical concentration. We have made a detailed study of co- existence of superconductivity and ferromagnetism in the concentration range close to the critical . We also study the effect of spin-spin interaction at T < Tm and spin-electron interactions on superconducting transition point. Superconductivity appears together with ferromagnetism but persists only until the ferromagnetic effect is not sufficiently largeenStudy of Co-Existence of SuperconductivityThesis