Superconductivity at 15.6 K in Calcium-doped Tb₁₋ₓCaₓFeAsO: the structure requirement for achieving superconductivity in the hole-doped 1111 phase

الأصل · EN

Superconductivity at about 15.6 K was achieved in Tb₁₋ₓCaₓFeAsO by partially substituting Tb³⁺ with Ca²⁺ in the nominal doping region x = 0.40 0.50. A detailed investigation was carried out in a typical sample with doping level of x = 0.44. The upper critical field of this sample was estimated to be 77 Tesla from the magnetic field dependent resistivity data. The domination of hole-like charge carriers in the low-temperature region was confirmed by Hall effect measurements. The comparison between the calcium-doped sample Pr₁₋ₓCaₓFeAsO (non-superconductive) and the Strontium-doped sample Pr₁₋ₓSrₓFeAsO (superconductive) suggests that a lager ion radius of the doped alkaline-earth element compared with that of the rare-earth element may be a necessary requirement for achieving superconductivity in the hole-doped 1111 phase.