Substrate, method of producing substrate, superconducting wire, and method of producing superconducting wire

A superconducting wire comprising:

• a copper layer,
• an alloy layer containing copper and nickel, formed on said copper layer,
• a nickel layer formed on said alloy layer,
• an intermediate layer formed on said nickel layer, and
• a superconducting layer formed on said intermediate layer,
• wherein a concentration of nickel in said alloy layer at an interface between said alloy layer and said nickel layer is greater than the concentration of nickel in said alloy layer at the interface between said alloy layer and said copper layer, and cooper does not diffuse to a surface of said nickel layer.

A method of producing a superconducting wire comprising the steps of:

• preparing a substrate having a nickel layer formed on a copper layer through plating,
• alloying a portion including a surface of said nickel layer while leaving a remaining portion of said nickel layer,
• epitaxial-growing an intermediate layer on said nickel layer after said step of alloying said nickel layer, and
• forming a superconducting layer on said intermediate layer.