Enhanced upper critical field, critical current density, and thermal activation energy in new ytterbium doped CeFeAsO0.9F0.1 superconductor

In this report, we have investigated the essential physical properties of Ce0.7Yb0.3FeAsO0.9F0.1 superconductor such as field dependent critical current density (Jc), thermal activation energy (U0), and upper critical field (Hc2). From the isothermal magnetization curves and size of the superconducting grains, the critical current density Jc of 2.3 × 106 A/cm2 at 2 K, 0.5 T was estimated using the Bean's model for this Yb doped superconductor. A gradual decrease of Jc and absence of peak effect were found on increasing magnetic field up to 5 T. Thermal activation energy (U0/kB = ∼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.