Magnetic detecting device having free layer or pinned layer formed by lamination of magnetic alloy and Cu layer and method of manufacturing magnetic detecting device

A method of manufacturing a magnetic detecting device comprising forming fixed magnetic layers whose magnetization direction is fixed, and a free magnetic layer which is formed between the fixed magnetic layers via non-magnetic material layers and whose magnetization direction varies by an external magnetic field,

• wherein at least a portion of the at least one of the fixed magnetic layers or the free magnetic layer is formed as a magnetic alloy layer whose composition formula is represented as XaYbZcαd and whose a composition ratio d of the element α is within a range which is greater than 0 at. % and not more than 17.5 at. %,
• the element X is at least one element selected from a group consisting of Co, Rh, Pt, Au, Pd, Ir, Ru, Ag, Zn, Cd and Fe,
• the element Y is at least one element selected from a group consisting of Mn, Fe, Ti, V, Zr, Nb, Hf, Ta, Cr, and Co,
• the element Z is at least one element selected from a group consisting of Al, Sn, In, Sb, Ga, Si, Ge, Pb, and Zn,
• the element α is at least one of Cu or Ni, and
• a, b, c, and d indicate average composition ratios (at. %) in the magnetic alloy layer and satisfy a relationship of a+b+c+d=100 at. %.