This invention is to provide a magnetic head consisting of NiFeMo alloy which assures excellent high frequency characteristic and makes easy formation of magnetic domain structure without any heat treatment and thereby contributes to improvement of magnetic recording capability. Magnetic material for a magnetic head includes Ni, Fe and Mo. The composition ratio of NiFeMo is selected under the condition where Ni is 77 to 82 atom %, Fe is 15 to 21 atom %, Mo is under 6 atom %, and magnetic strain constant .lambda.s is in the range of -1.times.10.sup.-6.ltoreq..lambda.s .ltoreq.10.sup.-6.

Magnetoresistive and spin valve heads have a layered structure. Common to each of the layered structures of these heads is the combination of a soft-magnetic layer of essentially NiFe near a spacer layer of essentially Ta, which is used for insuring (111) crystal orientation of the NiFe layer. An isolate layer is interposed between the spacer layer and the soft-magnetic layer to prevent a diffusion boundary from being created at the interface of these layers which tends to degrade the soft-magnetic property of the NiFe layer, especially when the thickness of the soft-magnetic layer is 10 and nm or less. The isolate layer is one of a composition in which the principal component is a magnetic element that is not solid soluble with Ta, a composition in which the principal component is a non-magnetic element that is not solid soluble with Ni and Fe, a composition in which the principal component is at least one of the elements of Co, Fe, Ti, V, Zr, Nb, Mo, Hf, W, Tc, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au; or a composition in which the principal component is of Co.sub.(100-X) Fe.sub.(X), where 20.gtoreq.X>O. The isolate layer has a structure that is amorphous, an fcc structure.

The invention is a laminated antiferromagnetically coupled (AFC) structure for use in a spin valve (SV) sensor or magnetic tunnel junction (MTJ) device, having two ferromagnetic films coupled together with an improved AFC film. Particularly the AFC film comprises an alloy material selected from the group consisting of Ru.sub.100-x m.sub.x, Os.sub.100-y m.sub.y, Ir.sub.100-y m.sub.y, Rh.sub.100-y,m.sub.y, Re.sub.100-z m.sub.z, and M.sub.100-x m.sub.x, where M is an alloy of two or more materials selected from the group consisting of Ru, Os, Ir, Rh, and Re, and where m is a material selected from the group consisting of W, Ta, Mo, Nb and alloys of two or more materials selected from W, Ta, Mo, and Nb, and where x is between approximately 5 and 95 at. %, y is between approximately 10 and 90 at. %, and z is between approximately 25 and 75 at. %. The sensors may be used in magnetic heads of hard disk drives.

A plurality of magnetic field sensing structures in a monolithic integrated circuit chip structure to provide output signals at outputs thereof of magnetic field changes provided therein from corresponding sources having poled pair structures with a gap space between them with adjacent ones of the magnetic field sensing structures that are interconnected with a circuit formed in the monolithic integrated circuit chip such as an amplifier. The paired pole structures may intersect a surface of the chip perpendicular to the major surfaces thereof or in one of, or a surface parallel to, the major surfaces thereof. A magnetic field generating structure may also be included in the chip.