Substitution effects of Ag/Cu and Al/Cu on Y123 samples: Hall anomaly and transport properties

Abstract

The Hall effect and its associated anomalies offer an important means for describing superconducting property in cuprate compounds. Here, we investigate the electron- and hole-doping effects (implemented through Al- and Ag-doping, respectively) on the Hall effect and transport properties of Y123 superconducting materials (YBa2Cu3-xXxO7-d; X= Ag, Al). The Hall anomaly, in both normal and vortex states, generally depends on multiple factors, such as temperature, magnetic field, and amount/type of doping. Specifically, for our samples, we observed that hole doping first enhances the critical temperature TC, whereas its excess beyond a threshold value (here x=0.15) decreases TC; electron doping, however, decreases TC. We also show how doping changes the critical current density JC at temperature 77K with magnetic field 9kOe. More importantly, all of our samples exhibited one Hall sign reversal. Interestingly, behavior of the Hall coefficient vs. temperature reveals that the Hall dip vs. magnetic field for Ag - doped samples shows a behavior opposite to that for Al-doped samples.