Concentration effect on high field pinning and transport behaviors in nano- Y₂ BaCuO₅ doped Sm-Ba-Cu-O superconductor

Recent studies indicate that the addition of nanoscale RE2 BaCuO5 (nmRE211) (RE=Y, Sm, and Nd) in melt-texture-grown Sm-Ba-Cu-O bulk material can enhance the critical current density (Jc), especially in high magnetic fields. It is known that the δ Tc pinning is the reason for high field peak effect in Jc -H curves. The Jc -H curves exhibit enhancement compared with those of undoped samples. The analysis of first derivations of R-T curves found two peaks in dRdT curves representing two characteristic temperatures in high magnetic fields, where the lower temperature is attributed to the weak superconducting phase. The relative strength of the two peaks varies with the concentration of nmY211 additions. This argument is consistent with microstructural observations and pinning analysis results.