A magneto-sensitive wire (magneto-sensitive body) made of a Co-based alloy having a composite structure in which crystal grains are dispersed in an amorphous phase. The Co-based alloy is, for example, a Co—Fe—Si—B-based alloy, and the total amount of Si and B is preferably 20 to 25 at % with respect to the Co-based alloy as a whole. Preferably, the average diameter of the crystal grains is 70 nm or less and the area ratio of the crystal grains is 10% or less to the composite structure as a whole. The magneto-sensitive wire has a circular cross section and the wire diameter is about 1 to 100 μm. Such a magneto-sensitive wire can be obtained, for example, through a heat treatment step of heating an amorphous wire composed of a Co-based alloy at a temperature equal to or higher than a crystallization start temperature and lower than a crystallization end temperature.

A magneto-sensitive wire for a magnetic sensor with both measurement range expansion and environment resistance performance improvement, includes a Co-based alloy containing more Fe than a reference composition that is amorphous overall and exhibits zero magnetostriction. The Co-based alloy may have an Fe ratio (Fe/(Co+Fe+Ni)) of 6.1% to 9.5%. The Fe ratio is an atomic fraction of the Fe amount with respect to the total amount of a magnetic element group consisting of Co, Fe, and Ni. By heating an amorphous wire of a Co-based alloy at a temperate at least equal to a crystallization start temperature and lower than a crystallization end temperature, allows the magneto-sensitive wire to have a composite structure in which crystal grains are dispersed in the amorphous phase. The magneto-sensitive wire's anisotropy field is, for example, 5 to 70 Oe and the stress sensitivity, indicative of magnetostriction, is −30 to 30 mOe/MPa.

The present disclosure relates to a magnetic multilayer composite that may include a core substrate layer, an outer magnetic layer overlying a first surface of the core substrate layer, and an inner magnetic layer underlying a second surface of the core substrate layer. The composite may include a magnetic volume ratio V.sub.M/V.sub.S of at least about 0.005, where V.sub.M is equal to the total volume of magnetic material in the composite and V.sub.S is the total volume of substrate. The composite may further include a permeability rating (X, Y), where the permeability rating (X, Y) is equal to a peak point (X, Y) along a plot of the imaginary part of magnetic permeability (μ″) of the composite plotted as a function of frequency, where X is within the range of 10 MHz to 10 GHz, and Y is greater than 100.

A soft magnetic alloy includes a main body and a surface layer. The main body has a soft magnetic alloy composition including Fe and Co. The surface layer is located on a surface side of the main body. A ratio of Co concentration to a sum of Co concentration and Fe concentration in the surface layer is Co/(Fe+Co). A distribution of Co/(Fe+Co) in a thickness direction of the surface layer includes a local minimum point and one or more local maximum points.

A soft magnetic alloy powder includes a particle body and a surface layer. The particle body comprises a soft magnetic alloy including Fe and Co. The surface layer is located on a surface side of the particle body. The surface layer includes one or more local maximum points of Si concentration and one or more local maximum points of Co concentration. The surface layer satisfies D.sub.Si≤D.sub.Co, in which D.sub.Si is a distance from an interface between the particle body and the surface layer to a first Si local maximum point L.sup.Si.sub.max, and D.sub.Co is a distance from the interface to a first Co local maximum point L.sup.Co.sub.max.

A soft magnetic alloy including an internal area having a soft magnetic type alloy composition including Fe and Co, a Co concentrated area existing closer to a surface side than the internal area and having a higher Co concentration than in the internal area, and a SB concentrated area existing closer to the surface side than the Co concentrated area and having a higher concentration of at least one element selected from Si and B than in the internal area.

A soft magnetic alloy comprising an internal area having a soft magnetic type alloy composition including Fe and Co, a Co concentrated area existing closer to a surface side than the internal area and having a higher Co concentration than in the internal area, a SB concentrated area existing closer to the surface side than the Co concentrated area and having a higher concentration of at least one element selected from Si and B than in the internal area, and a Fe concentrated area including Fe existing closer to the surface side than the SB concentrated area; wherein a crystalized area ratio of the SB concentrated area represented by S.sub.SB.sup.cry/S.sub.SB and a crystalized area ratio of the Fe concentrated area represented by S.sub.Fe.sup.cry/S.sub.Fe, satisfy a relation of (S.sub.SB.sup.cry/S.sub.SB)<(S.sub.Fe.sup.cry/S.sub.Fe).

Provided are: a novel magnetic material having high magnetic stability, in particular, having an extremely high saturation magnetization; and a method for producing the same, wherein the magnetic material, due to having a higher saturation magnetization than ferrite magnetic materials and a higher electrical resistivity than existing metallic magnetic materials, resolves problems such as eddy current loss. According to the present invention, Co-ferrite nanoparticles obtained by wet synthesis are reduced in hydrogen and subjected to grain growth, and bcc- or fcc-(Fe, Co) phases and Co-enriched phases are nano-dispersed using phase separation via a disproportionation reaction to prepare a magnetic material powder. In addition, the magnetic material powder is sintered into a solid magnetic material.

A method for producing a magnetic core includes a processing step of giving a desired shape to a strip made of an alloy composition, a heat-treating step of forming bcc-Fe crystals, and then a stacking step of obtaining a magnetic core having a shape. Here, the alloy composition is Fe—B—Si—P—Cu—C and has an amorphous phase as a primary phase. In the heat-treating step, the strip is heated up to a temperature higher than a crystallization temperature of the alloy composition at a high heating rate.

A soft magnetic alloy including an internal area having a soft magnetic type alloy composition including Fe and Co, a Co concentrated area existing closer to a surface side than the internal area and having a higher Co concentration than in the internal area, and a SB concentrated area existing closer to the surface side than the Co concentrated area and having a higher concentration of at least one element selected from Si and B than in the internal area.