Plating solution, process for producing a structure with the plating solution, and apparatus employing the plating solution

A solution comprising ionic Fe supplied to the solution by an iron salt, ionic Pt supplied to the solution by a hexachloroplatinate(IV) salt, at a molar ratio of the ionic Fe to the ionic Pt ranging from 0.75 to 3, tartaric acid as a complexing agent, and chloride ion in an amount in excess of any chloride ion supplied to the solution by the iron salt and the hexachloroplatinate(IV) salt,

• wherein the solution is such that it is capable of depositing FePt or FePtCu when plating using the solution is performed,
• wherein a concentration of the ionic Fe is from 0.01 mol/L to 0.05 mol/L,
• wherein a pH of the solution is from 7.0 to 9.0, and
• wherein the chloride ion concentration is not lower than a molar concentration of the hexachloroplatinate(IV) salt.