Upper critical fields and critical current density of single crystal

The transport properties, upper critical fields, superconducting anisotropy, and critical current density of an iso-valent phosphorus-doped BaFe2As2 single crystal close to optimum doping are investigated in this report. Temperature dependent resistivity and susceptibility show a superconducting transition temperature, T c , just below 31 K both with sharp transitions. The upper critical field parallel to the ab-plane, H c 2 a b , is above 77 T while that along the c -axis direction, H c 2 c , is just above 36 T, yielding a low superconducting anisotropy ratio ∼ 2 . The estimated inter-plane coherence length based on the Ginzburg–Landau (G-L) theory indicates BaFe2(As0.68P0.32)2 is still above the point for a dimensional crossover inferring the superconducting layers are not weakly-coupled in this system. The critical current density at 5 K obtained from magnetization loops measurement show a modest J c as high as 105 A/cm2.