A rotating magnetic physical unclonable function (PUF) is disclosed. Rotating the PUF enables robust low cost PUF readers. PUF may be incorporated into a user-replaceable supply item for an imaging device. A PUF reader may be incorporated into an imaging device to read the PUF. Other systems and methods are disclosed.

A magnetic film includes iron and copper distributed between opposing first and second major surfaces of the magnetic film. The copper has a first atomic concentration C1 at a first depth d1 from the first major surface and a peak second atomic concentration C2 at a second depth d2 from the first major surface, d2>d1, C2/C15.

An inductor includes a wire including a conducting line, and an insulating film disposed on an entire circumferential surface of the conducting line, and a magnetic layer embedding the wire. The magnetic layer contains a magnetic particle. The magnetic layer includes a first layer in contact with the circumferential surface of the wire, a second layer in contact with the surface of the first layer . . . and the n-th layer (n is a positive number of 3 or more) in contact with the surface of the (n1)th layer. In the two layers adjacent to each other in the magnetic layer, the relative magnetic permeability of the layer closer to the wire is lower than the relative magnetic permeability of the layer farther from the wire.

An inductor includes a wire, and a magnetic layer covering the wire. The wire includes a conducting line, and an insulating layer covering the conducting line. The magnetic layer includes a magnetic particle and a binder. In a peripheral region of the wire, a filling rate of the magnetic particle is 40% by volume or more. The peripheral region is a region of the magnetic layer traveling outwardly from an outer peripheral surface of the wire by 1.5 times an average of the longest length and the shortest length from the center of gravity C of the wire to an outer surface of the wire in a cross-sectional view.

The present invention provides a bonded magnet having good heat resistance. The present invention relates to a bonded magnet containing a SmFeN magnetic powder, nylon 12, and a hexafluoroisopropanol-unextractable component. The present invention also relates to a method of preparing a bonded magnet, including: bringing a raw material bonded magnet containing a SmFeN magnetic powder and nylon 12 into contact with an amorphizing agent; and heat-treating the raw material bonded magnet in contact with the amorphizing agent.

A physical unclonable function (PUF) apparatus having magnetic particles is disclosed. The magnetic field data and the image view of the magnetic particles in the PUF apparatus are difficult to counterfeit. A PUF apparatus may be incorporated into a user-replaceable supply item for an imaging device. Further, a PUF reader may be incorporated into an imaging device to read the PUF. Other systems are disclosed.

A bulk permanent magnetic material may include between about 5 volume percent and about 40 volume percent Fe.sub.16N.sub.2 phase domains, a plurality of nonmagnetic atoms or molecules forming domain wall pinning sites, and a balance soft magnetic material, wherein at least some of the soft magnetic material is magnetically coupled to the Fe.sub.16N.sub.2 phase domains via exchange spring coupling. In some examples, a bulk permanent magnetic material may be formed by implanting N+ ions in an iron workpiece using ion implantation to form an iron nitride workpiece, pre-annealing the iron nitride workpiece to attach the iron nitride workpiece to a substrate, and post-annealing the iron nitride workpiece to form Fe.sub.16N.sub.2 phase domains within the iron nitride workpiece.

A bulk permanent magnetic material may include between about 5 volume percent and about 40 volume percent Fe.sub.16N.sub.2 phase domains, a plurality of nonmagnetic atoms or molecules forming domain wall pinning sites, and a balance soft magnetic material, wherein at least some of the soft magnetic material is magnetically coupled to the Fe.sub.16N.sub.2 phase domains via exchange spring coupling. In some examples, a bulk permanent magnetic material may be formed by implanting N+ ions in an iron workpiece using ion implantation to form an iron nitride workpiece, pre-annealing the iron nitride workpiece to attach the iron nitride workpiece to a substrate, and post-annealing the iron nitride workpiece to form Fe.sub.16N.sub.2 phase domains within the iron nitride workpiece.

A magnetic sheet having a magnetic material particle comprising a hexaferrite and a nanofiber matrix made of two or more nanofibers, wherein the magnetic material particle is dispersed in the nanofiber matrix. A manufacturing method thereof and a speaker including the magnetic sheet are also provided.

Microspheres, populations of microspheres, and methods for forming microspheres are provided. One microsphere configured to exhibit fluorescent and magnetic properties includes a core microsphere and a magnetic material coupled to a surface of the core microsphere. About 50% or less of the surface of the core microsphere is covered by the magnetic material. The microsphere also includes a polymer layer surrounding the magnetic material and the core microsphere. One population of microspheres configured to exhibit fluorescent and magnetic properties includes two or more subsets of microspheres. The two or more subsets of microspheres are configured to exhibit different fluorescent and/or magnetic properties. Individual microspheres in the two or more subsets are configured as described above.