Oxide superconductor and method for manufacturing the same

An oxide superconductor, comprising:

• REBa2Cu3O7-x (RE being one element selected from a “RE element group” of Pr, Nd, Sm, Eu, Gd, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu) including fluorine and carbon, the fluorine having a concentration of not less than 2.0×1016 atoms/cc and not more than 5.0×1019 atoms/cc, the carbon having a concentration of not less than 1.0×1018 atoms/cc and not more than 5.0×1020 atoms/cc, RE including at least three types of metallic elements (M1, M2, and M3) in a superconducting layer, the three types of metallic elements being any element of the RE element group selected in order, R(M1) 20 mol % and R(M2) 60 mol % and R(M3) 20 mol % being satisfied, R(M1) being an average metallic element ratio of M1 in M1+M2+M3, R(M2) being an average metallic element ratio of M2 in M1+M2+M3, R(M3) being an average metallic element ratio of M3 in M1+M2+M3,
• the REBa2Cu3O7-x having a single perovskite structure oriented in a c-axis,
• Msmax≥1.5×Msmin being satisfied, if R(M1) is equal to or smaller than R(M3), Ms is M1, in the other case Ms is M3, Msmax and Msmin respectively being a maximum value and minimum value of a concentration of Ms at a position at 50% of an average superconducting film thickness of a cross section including the c-axis from a non-superconducting basis to top of the superconducting layer,
• wherein the superconductor comprise a maximum of 20 mol % of PrBCO non-superconducting units.