“…Therefore, it is expected that Bi-2212 system is a more appropriate candidate for the study of element substitution in Cu site. In previous studies, when Cu site was occupied by other 3d metal, such as Fe, Co, Ni, Zn and Mn, the superconducting transition temperature (T c ) of Bi-2212 system was suppressed, which was mainly due to pair-breaking effect [2][3][4][5][6]. The pair-breaking effect could lead to the emergence of insulating ground state, which originates from carrier localization in the vicinity of the Fermi level.…”