A motor rotor includes an iron core. A mounting groove is recessed from an end surface of the iron core and extends in a direction from a middle of the iron core to an outer peripheral surface of the iron core. The motor rotor further includes a first magnet and a second magnet embedded in the mounting groove and arranged at an interval along an extension direction of the mounting groove. The first magnet is fixed at a radial outer side of the second magnet. A magnetization direction of each of the first magnet and the second magnet is perpendicular to the extension direction of the mounting groove. A coercive force of the first magnet being greater than a coercive force of the second magnet.

A method for producing an RFeB system sintered magnet according to the present invention includes: a process (S1) of preparing a lump of HDDR-treated raw material alloy that contains a polycrystalline substance including crystal grains having an average grain size of 1 μm or less in terms of an equivalent circle diameter calculated from an electron micrograph image, by an HDDR treatment including steps of heating a lump of RFeB system alloy containing 26.5 to 29.5% by weight of the rare-earth element R, in a hydrogen atmosphere at a temperature between 700 and 1,000° C., and changing the atmosphere to vacuum while maintaining the temperature within a range from 750 to 900° C.; a process (S2) of preparing a lump of raw material alloy having a high rare-earth content by heating the lump of HDDR-treated raw material alloy at a temperature between 700 and 950° C. in a state where the HDDR-treated raw material alloy is in contact with a contact substance including a second alloy that contains the rare-earth element R at a higher content ratio than a content ratio of the rare-earth element R in the RFeB system alloy; a process (S3) of preparing raw material alloy powder by fine pulverization of the lump of raw material alloy having a high rare-earth content into powder having an average particle size of 1 μm or less; an orienting process (S4) including steps of placing the raw material alloy powder in a mold, and applying a magnetic field to the raw material alloy powder without conducting compression molding; and a sintering process (S5) including a step of heating the oriented raw material alloy powder at a temperature between 850 and 1,050° C.

An oxide superconducting bulk magnet able to prevent breakage of a superconducting bulk member and able to give a sufficient amount of total magnetic flux at a superconducting bulk member surface even under high magnetic field strength conditions, comprising an oxide superconducting bulk laminate formed from sheet-shaped oxide superconducting bulk members and high strength reinforcing members arranged between the stacked oxide superconducting bulk members, the outer circumference of the oxide superconducting bulk laminate being provided with an outer circumference reinforcing member.

An oxide superconducting bulk magnet able to prevent breakage of a superconducting bulk member and able to give a sufficient amount of total magnetic flux at a superconducting bulk member surface even under high magnetic field strength conditions, comprising an oxide superconducting bulk laminate formed from sheet-shaped oxide superconducting bulk members and high strength reinforcing members arranged between the stacked oxide superconducting bulk members, the outer circumference of the oxide superconducting bulk laminate being provided with an outer circumference reinforcing member.

A sintered magnet contains Sm—Fe—N-based crystal grains and has high coercivity; and a magnetic powder is capable of forming a sintered magnet without lowering the coercivity even if heat is generated in association with the sintering. A sintered magnet comprises a crystal phase composed of a plurality of Sm—Fe—N-based crystal grains and a nonmagnetic metal phase present between the Sm—Fe—N crystal grains adjacent to each other, wherein a ratio of Fe peak intensity I.sub.Fe to SmFeN peak intensity I.sub.SmFeN measured by an X-ray diffraction method is 0.2 or less. A magnetic powder comprises Sm—Fe—N-based crystal particles and a nonmagnetic metal layer covering surfaces of the Sm—Fe—N crystal particles.

Provided is a ferromagnetic powder for magnetic recording, in which an activation volume is 800 nm.sup.3 to 1,500 nm.sup.3, an average plate ratio is 2.0 to 5.0, a rare earth atom content is 0.5 atom % to 5.0 atom %, and an aluminum atom content is greater than 10.0 atom % and equal to or smaller than 20.0 atom %, with respect to 100 atom % of iron atom, and the ferromagnetic powder is a plate-shaped hexagonal strontium ferrite powder having a rare earth atom surface layer portion uneven distribution and an aluminum atom surface layer portion uneven distribution, and a magnetic recording medium including this ferromagnetic powder for magnetic recording in a magnetic layer.

Provided is a ferromagnetic powder for magnetic recording, in which an activation volume is 800 nm.sup.3 to 1,500 nm.sup.3, an average plate ratio is 2.0 to 5.0, a rare earth atom content is 0.5 atom % to 5.0 atom %, and an aluminum atom content is greater than 10.0 atom % and equal to or smaller than 20.0 atom %, with respect to 100 atom % of iron atom, and the ferromagnetic powder is a plate-shaped hexagonal strontium ferrite powder having a rare earth atom surface layer portion uneven distribution and an aluminum atom surface layer portion uneven distribution, and a magnetic recording medium including this ferromagnetic powder for magnetic recording in a magnetic layer.

A method for producing a powdered starting material, which is provided for production of rare earth magnets, including includes the following steps: pulverizing an alloy, including at least one rare earth metal, wherein a powdered intermediate product is formed from the alloy including the at least one rare earth metal, and carrying out at least one classification aimed at particle size and/or particle density for the powdered intermediate product. A fraction of the powdered intermediate product, which is formed by the at least one classification, is used for fabrication of rare earth magnets. Furthermore, at least one dynamic classifier is provided, implementing at least one classification directed at particle size and/or particle density for the powdered intermediate product and thereby separates the fraction from the powdered intermediate product, which forms the starting material for manufacturing rare earth magnets.

In an exemplary embodiment, a multilayer coil component includes: a substrate body; and a coil embedded in the substrate body and containing a wound conductor; wherein the substrate body has: magnetic layers containing multiple metal magnetic grains, provided around conductor layers that constitute parts of the wound conductor in a direction roughly orthogonal to the coil axis of the coil; and multiple high-hardness insulating grains harder than the multiple metal magnetic grains and smaller in average grain size than the multiple metal magnetic grains, provided between a pair of the conductor layers adjacent to each other in the direction of the coil axis and also between a pair of the magnetic layers adjacent to each other in the direction of the coil axis. The multilayer coil component can prevent shorting in the wound conductor while increasing the inductance.

In an exemplary embodiment, a multilayer coil component includes: a substrate body; and a coil embedded in the substrate body and containing a wound conductor; wherein the substrate body has: magnetic layers containing multiple metal magnetic grains, provided around conductor layers that constitute parts of the wound conductor in a direction roughly orthogonal to the coil axis of the coil; and multiple high-hardness insulating grains harder than the multiple metal magnetic grains and smaller in average grain size than the multiple metal magnetic grains, provided between a pair of the conductor layers adjacent to each other in the direction of the coil axis and also between a pair of the magnetic layers adjacent to each other in the direction of the coil axis. The multilayer coil component can prevent shorting in the wound conductor while increasing the inductance.