Laminate film for current-perpendicular-to-plane giant magnetoresistive element, current-perpendicular-to-plane giant magnetoresistive element, and use therefor

Provided is a laminate film for a current-perpendicular-to-plane giant magnetoresistive (CPP-GMR) element, said laminate film exhibiting high sensitivity, and demonstrating excellent linearity between an external magnetic field and a resistance value. The laminate film for a current-perpendicular-to-plane giant magnetoresistive element is provided so as to allow for the formation of a strong antiferromagnetic interlayer exchange coupling. The problem of the present invention is solved through a laminate film for a current-perpendicular-to-plane giant magnetoresistive element, said laminate film having a base, and a laminate section provided on the base and obtained by alternately laminating a plurality of free magnetic layers and a plurality of non-magnetic layers, wherein at least three free magnetic layers are provided, and at least one of the non-magnetic layers has a thickness allowing for the formation, between the pair of free magnetic layers contacting both surfaces of said non-magnetic layer, of an antiferromagnetic interlayer exchange coupling, or through a laminate film for a current-perpendicular-to-plane giant magnetoresistive element, said laminate film having a base, a laminate section provided on the base and obtained by alternately laminating at least two free magnetic layers and at least one non-magnetic layer, an underlayer provided, as desired, between the base and the laminate section, and a cap layer provided, as desired, above the laminate section, wherein the at least one non-magnetic layer has a thickness allowing for the formation, between the pair of free magnetic layers contacting both surfaces of said non-magnetic layer, of an antiferromagnetic interlayer exchange coupling, and the surface roughness Ra of at least one from among the surface of the underlayer, an interface between a magnetic layer and the non-magnetic layer, and the surface of the cap layer is at most 0.75 nm.