Enhanced upper critical field, critical current density, and thermal activation energy in new ytterbium doped CeFeAsO_(0.9)F_(0.1) superconductor

摘要

In this report, we have investigated the essential physical properties of Ce_(0.7)Yb_(0.3)FeAsO_(0.9)F_(0.1) superconductor such as field dependent critical current density (J_c), thermal activation energy (U_0), and upper critical field (H_(c2)). From the isothermal magnetization curves and size of the superconducting grains, the critical current density J_c of 2.3 × 10~6A/cm~2 at 2K, 0.5 T was estimated using the Bean's model for this Yb doped superconductor. A gradual decrease of J_c and absence of peak effect were found on increasing magnetic field up to 5T. Thermal activation energy (U_0/k_B = ～2500 K) calculated from Arrhenius plots at low magnetic field (0.5 T) indicates a strong flux pinning potential might be co-existing with applied magnetic field. Our results suggest that this new Yb doped superconductor is a possible practical high temperature superconductor under certain magnetic field and temperature.