A well perception of superconductivity mechanism in high-temperature superconductors has raised an unsolved question within the superconductivity field. There are several ways to investigate the mechanism of high-temperature superconductors including the replacement of various ingredients in the composition of high-temperature superconductors. Throughout this study, the high-temperature superconducting samples of YBa 2 Cu 3 O 7 have been investigated through substituting the small amounts of magnetic elements Fe, Li, Mn, and Co in the Y position. Concerning the BCS theory, the electrons pairing is defined through the usage of phonon and also, the magnetism opposing the superconductivity. With the given regard, a very low concentration of Li elements with high phonon frequency and magnetic elements of Co, Mn and Fe have been chosen to use. It is noteworthy to state that, the samples were made using standard sol-gel method. The analysis of AC magnetic susceptibility, DC electrical resistance and critical current density have been conducted on the samples. The electrical resistance-temperature figure reveals the increasing at the critical temperature of superconductivity (Tc) for the doped samples of iron and cobalt, which can be verified through the magnetic susceptibility figure. Moreover, as can be seen from the electrical resistance figures of the samples within the range of high transition temperatures (normal phase), the resistance variations in terms of temperature are linearly decreased, which indicates the normal metallic behavior of the samples. The pinning strength of the flux and also the intergranular connections quality of the samples have been measured through the electrical-resistance analysis subjected to an external magnetic field up to the size of a Tesla. Thereafter, the pinning potential of the samples are calculated from the figures. The resistance transition along with reduction in temperature consists of two stages including: firstly, a striking decrease in T onset owing to superconductivity transition inside the grains and Secondly, a slight reduction about the zero resistance in electrical resistance, which could be attributed to the intergranular resistance. The mentioned transition width provides beneficial information on intergranular pairing. Investigating the electrical-resistance broadening of the samples subjected to external magnetic field reveals that the intergranular bonding for doped iron and cobalt samples has strikingly increased. On the contrary, verified through J c measurement, the intergranular bonding for the doped of manganese and lithium has decreased. Increasing the transition superconductivity temperature of cobalt and iron in YBa 2 Cu 3 O 7 superconductor is in contrast with general existing aspects, which holds the opinion that an increase in magnetic impurities in superconductors composition would lead to failure in electrons pairing and consequently reduce the transition superconductivity temperature. This project has led us to state that the presence of cobalt and iron magnetic ions in the composition, not only caused failure in the carriers pairing, but also, they have optimally improved the superconductivity characteristics. The novelty of these findings categorized in copper compositions could shed a light on new theorems based upon the electrons pairing due to spin oscillations.
