Patent ID: 7616410

Claim:
A magnetic detecting element comprising: a pinned magnetic layer whose magnetization direction is fixed; and a free magnetic layer which is formed on the pinned magnetic layer with a non-magnetic layer interposed therebetween and whose magnetization direction varies in accordance with an external magnetic field, wherein the free magnetic layer is formed of NiFeX alloy layer only or NiFeX alloy layer and a diffusion preventive layer formed of CoFe (an element X is composed of at least one element selected from Cu, Sc, Ti, Zn, Zr, Hf, Au, Ag, Mn, and Al), an average composition ratio of the element X is in the range of 5 to 20 atomic percent, and regions where the composition ratio of the element X increases from the lower surface toward the upper surface of the NiFeX alloy layer, and regions where the composition ratio of the element X decreases from the lower surface toward the upper surface of the NiFeX alloy layer are alternately formed.