Abstract: In some examples, a device includes a magnetic tunnel junction including a first Weyl semimetal layer, a second Weyl semimetal layer, and a dielectric layer positioned between the first and second Weyl semimetal layers. The magnetic tunnel junction may have a large tunnel magnetoresistance ratio, which may be greater than five hundred percent or even greater than one thousand percent.

Abstract: A magnetic device may include a layer stack including a work function structure, a dielectric layer, and a ferromagnetic layer, where the ferromagnetic layer is positioned between the work function structure and the dielectric layer. The work function structure is configured to deplete electrons from the ferromagnetic layer or accumulate electrons in the ferromagnetic layer. A magnetization orientation of the ferromagnetic layer is configured to be switched by a voltage applied across the layer stack or by a voltage applied across or through the work function structure.

Abstract: A magnetic device may include a layer stack including a work function structure, a dielectric layer, and a ferromagnetic layer, where the ferromagnetic layer is positioned between the work function structure and the dielectric layer. The work function structure is configured to deplete electrons from the ferromagnetic layer or accumulate electrons in the ferromagnetic layer. A magnetization orientation of the ferromagnetic layer is configured to be switched by a voltage applied across the layer stack or by a voltage applied across or through the work function structure.

Abstract: A magnetic device includes a layer stack comprising a first ferromagnetic layer; a spacer layer on the first ferromagnetic layer; a second ferromagnetic layer on the spacer layer; a dielectric barrier layer on the second ferromagnetic layer; an insertion layer positioned between the second ferromagnetic layer and the dielectric barrier layer; and a fixed layer or an electrode on the dielectric barrier layer. In some examples, a magnetic orientation of the second ferromagnetic layer is switched by a bias voltage across the layer stack without application of an external magnetic field; an antiferromagnetic coupling of the first and second ferromagnetic layers is increased by the bias voltage applying a negative charge to the fixed layer or the electrode, and the antiferromagnetic coupling of the first and second ferromagnetic layers is decreased by the bias voltage applying a positive charge to the fixed layer or the electrode.

Abstract: In some examples, a device includes a dielectric material, a ferromagnetic material, and a topological material positioned between the dielectric material and the ferromagnetic material. The device is configured to trap electric charge inside the dielectric material or at an interface of the dielectric material and the topological material. The device is configured to switch a magnetization state of the ferromagnetic material based on a current through the topological material or based on a voltage in the topological material.

Abstract: Techniques are disclosed concerning applied magnetic field synthesis and processing of iron nitride magnetic materials. Some methods concern casting a material including iron in the presence of an applied magnetic field to form a workpiece including at least one ironbased phase domain including uniaxial magnetic anisotropy, wherein the applied magnetic field has a strength of at least about 0.01 Tesla (T). Also disclosed are workpieces made by such methods, apparatus for making such workpieces and bulk materials made by such methods.

Abstract: An example composition may include a plurality of grains including an iron nitride phase. The plurality of grains may have an average grain size between about 10 nm and about 200 nm. An example technique may include treating a composition including a plurality of grains including an iron-based phase to adjust an average grain size of the plurality of grains to between about 20 nm and about 100 nm. The example technique may include nitriding the plurality of grains to form or grow an iron nitride phase.

Abstract: A permanent magnet may include a Fe16N2 phase in a strained state. In some examples, strain may be preserved within the permanent magnet by a technique that includes etching an iron nitride-containing workpiece including Fe16N2 to introduce texture, straining the workpiece, and annealing the workpiece. In some examples, strain may be preserved within the permanent magnet by a technique that includes applying at a first temperature a layer of material to an iron nitride-containing workpiece including Fe16N2, and bringing the layer of material and the iron nitride-containing workpiece to a second temperature, where the material has a different coefficient of thermal expansion than the iron nitride-containing workpiece. A permanent magnet including an Fe16N2 phase with preserved strain also is disclosed.

Abstract: Example nanoparticles may include an iron-based core, and a shell. The shell may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example alloy compositions may include an iron-based grain, and a grain boundary. The grain boundary may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example techniques for forming iron-based core-shell nanoparticles may include depositing a shell on an iron-based core. The depositing may include immersing the iron-based core in a salt composition for a predetermined period of time. The depositing may include milling the iron-based core with a salt composition for a predetermined period of time. Example techniques for treating a composition comprising core-shell nanoparticles may include nitriding the composition.

Abstract: The disclosure describes techniques for forming nanoparticles including Fe16N2 phase. In some examples, the nanoparticles may be formed by first forming nanoparticles including iron, nitrogen, and at least one of carbon or boron. The carbon or boron may be incorporated into the nanoparticles such that the iron, nitrogen, and at least one of carbon or boron are mixed. Alternatively, the at least one of carbon or boron may be coated on a surface of a nanoparticle including iron and nitrogen. The nanoparticle including iron, nitrogen, and at least one of carbon or boron then may be annealed to form at least one phase domain including at least one of Fe16N2, Fe16(NB)2, Fe16(NC)2, or Fe16(NCB)2.

Abstract: A permanent magnet may include a Fe16N2 phase in a strained state. In some examples, strain may be preserved within the permanent magnet by a technique that includes etching an iron nitride-containing workpiece including Fe16N2 to introduce texture, straining the workpiece, and annealing the workpiece. In some examples, strain may be preserved within the permanent magnet by a technique that includes applying at a first temperature a layer of material to an iron nitride-containing workpiece including Fe16N2, and bringing the layer of material and the iron nitride-containing workpiece to a second temperature, where the material has a different coefficient of thermal expansion than the iron nitride-containing workpiece. A permanent magnet including an Fe16N2 phase with preserved strain also is disclosed.

Abstract: A bulk permanent magnetic material may include between about 5 volume percent and about 40 volume percent Fe16N2 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 Fe16N2 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 Fe16N2 phase domains within the iron nitride workpiece.

Abstract: The disclosure describes techniques for forming hard magnetic materials including ??-Fe16N2 using chemical vapor deposition or liquid phase epitaxy and hard materials formed according to these techniques. A method comprises heating an iron source to form a vapor comprising an iron-containing compound; depositing iron from the vapor comprising the iron-containing compound and nitrogen from a vapor comprising a nitrogen-containing compound on a substrate to form a layer comprising iron and nitrogen; and annealing the layer comprising iron and nitrogen to form at least some crystals comprising ??-Fe16N2.

Abstract: The disclosure describes techniques for forming nanoparticles including Fe16N2 phase. In some examples, the nanoparticles may be formed by first forming nanoparticles including iron, nitrogen, and at least one of carbon or boron. The carbon or boron may be incorporated into the nanoparticles such that the iron, nitrogen, and at least one of carbon or boron are mixed. Alternatively, the at least one of carbon or boron may be coated on a surface of a nanoparticle including iron and nitrogen. The nano particle including iron, nitrogen, and at least one of carbon or boron then may be annealed to form at least one phase domain including at least one of Fe16N2, Fe16(NB)2, Fe16(NC)2, or Fe16(NCB)2.

Abstract: A magnetic device may include a layer stack. The layer stack may include a first ferromagnetic layer; a spacer layer on the first ferromagnetic layer; a second ferromagnetic layer on the spacer layer; and a dielectric barrier layer on the second ferromagnetic layer. In some examples, the layer stack may also include an additional ferromagnetic layer and an additional spacer layer. The magnetic device also may include a voltage source configured to apply a bias voltage across the layer stack to cause switching of a magnetic orientation of the second ferromagnetic layer without application of an external magnetic field.

Abstract: A logic-memory cell includes a spin-orbit torque device having first, second and third terminals configured such that current between the second and third terminals is capable of changing a resistance between the first and second terminals. In the cell, a first transistor is connected between a logic connection line and the first terminal of the spin-orbit torque device and a second transistor is connected between the logic connection line and the third terminal of the spin-orbit torque device.

Abstract: A magnetic device may include a layer stack. The layer stack may include a first ferromagnetic layer; a spacer layer on the first ferromagnetic layer; a second ferromagnetic layer on the spacer layer; and a dielectric barrier layer on the second ferromagnetic layer. In some examples, the layer stack may also include an additional ferromagnetic layer and an additional spacer layer. The magnetic device also may include a voltage source configured to apply a bias voltage across the layer stack to cause switching of a magnetic orientation of the second ferromagnetic layer without application of an external magnetic field.

Abstract: Example nanoparticles may include an iron-based core, and a shell. The shell may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example alloy compositions may include an iron-based grain, and a grain boundary. The grain boundary may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example techniques for forming iron-based core-shell nanoparticles may include depositing a shell on an iron-based core. The depositing may include immersing the iron-based core in a salt composition for a predetermined period of time. The depositing may include milling the iron-based core with a salt composition for a predetermined period of time. Example techniques for treating a composition comprising core-shell nanoparticles may include nitriding the composition.

Abstract: Techniques are disclosed concerning applied magnetic field synthesis and processing of iron nitride magnetic materials. Some methods concern casting a material including iron in the presence of an applied magnetic field to form a workpiece including at least one iron-based phase domain including uniaxial magnetic anisotropy, wherein the applied magnetic field has a strength of at least about 0.01 Tesla (T). Also disclosed are workpieces made by such methods, apparatus for making such workpieces and bulk materials made by such methods.

Abstract: In general, the disclosure is directed to bulk iron-nitride materials having a polycrystalline microstructure having pores including a plurality of crystallographic grains surrounded by grain boundaries, where at least one crystallographic grain includes an iron-nitride phase including any of a body centered cubic (bcc) structure, a body centered tetragonal (bct), and a martensite structure. The disclosure further describes techniques producing a bulk iron-nitride material having a polycrystalline microstructure, including: melting an iron source to obtain a molten iron source; fast belt casting the molten iron source to obtain a cast iron source; cooling and shaping the cast iron source to obtain a bulk iron-containing material having a body-centered cubic (bcc) structure; annealing the bulk iron-containing material at an austenite transformation temperature and subsequently cooling the bulk iron-containing material; and nitriding the bulk iron-containing material to obtain the bulk iron-nitride material.