University of Minnesota

Data Storage Institute

Ut-battelle, Inc.

Carnegie Mellon University

Agency for Science, Technology and Research

University of Tennessee Research Foundation

Jian-Ping Wang

Yanfeng Jiang

Mahdi Jamali

Delin Zhang

Bin Ma

Jinming Liu

Yiming Wu

Xiaowei Zhang

Orlando Rios

Michael P Brady

Shihai He

Craig A Bridges

Edgar Lara-Curzio

Mo Li

Md Aminul Mehedi

Lawrence F Allard

Gerard Michael Ludtka

Fan Zhang

Yuanpeng Li

Protyush Sahu

Zhengyang Zhao

Mahendra Dc

Yang Lv

Jonathan D Harms

Md Tofizur Rahman

Thomas Peterson

Sara A Majetich

Chengguo Xing

Guannan Guo

Sachin S Sapatnekar

Mukund Bapna

YanFeng Jiang

Angeline Klemm Smith

Balasubramanian Srinivasan

Jianxin Zhu

Claire T Hovland

Walter C Low

Tow Chong Chong

Jianzhong Shi

David J Lilja

Jingsheng Chen

Ulya R Karpuzcu

Xiaofeng Yao

Seidikkurippu Nellainayagam Piramanayagam

Hyung-il Kim

Roberta A Meisner

Timothy A Bloomquist

Tony Low

Thomas Yun Fook Liew

Yunjie Chen

Duarte José Pereira De Sousa

Patrick Quarterman

Cesar Octavio Ascencio

Michael Salonik Resch

Tie Jun Zhou

Masoud Zabihi

Lea Peng Tan

Zhaoxin Liang

Anthony William Hurben

Zamshed I Chowdhury

Shruti R Patil

Andrew P Lyle

Junyang Chen

Jing Ying

Haibao Zhao

Hao Wang

Liang Tu

Yi Wang

Wang Yi

Meghna G Mankalale

Andre Mkhoyan

Danielle Hickey

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.

Iron-nitride magnet by nitriding a porous structure

A permanent magnet may include a FeNphase constitution. In some examples, the permanent magnet may be formed by a technique that includes straining an iron wire or sheet comprising at least one iron crystal in a direction substantially parallel to a <001> crystal axis of the iron crystal; nitridizing the iron wire or sheet to form a nitridized iron wire or sheet; annealing the nitridized iron wire or sheet to form a FeNphase constitution in at least a portion of the nitridized iron wire or sheet; and pressing the nitridized iron wires and sheets to form bulk permanent magnet.

Iron nitride permanent magnet and technique for forming iron nitride permanent magnet

A method may include annealing a material including iron and nitrogen in the presence of an applied magnetic field to form at least one FeNphase domain. The applied magnetic field may have a strength of at least about 0.2 Tesla (T).

Applied magnetic field synthesis and processing of iron nitride magnetic materials

The disclosure describes a method that includes forming a soft magnetic material by a technique including melt spinning. The soft magnetic material includes at least one of: at least one of an α″-Fe(NZ)phase domain or an α'-Fe(NZ), where Z includes at least one of C, B, or O, and where x is a number greater than zero and less than one; or at least one of an α″-FeNphase domain or an α′-FeN phase domain, and at least one of an α″-FeZphase domain or an α′-FeZ phase domain.

Magnetic material including α″-Fe(NZ)or a mixture of α″-FeZand α″-FeN, where Z includes at least one of C, B, or O

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.

The disclosure is directed to an iron-nitride material having a polycrystalline microstructure including a plurality of elongated crystallographic grains with grain boundaries, the iron-nitride material including at least one of an α″-FeNphase and a body-center-tetragonal (bct) phase comprising Fe and N. The disclosure is also directed a method producing an iron-nitride material. The method includes some combinations of preparing a raw material comprising iron, carrying out a microstructure build-up by annealing the prepared raw material at an elevated temperature and subsequently quenching the prepared raw material to produce a microstructure build-up material, annealing the microstructure build-up material, reducing the microstructure build-up material in a hydrogen environment, nitriding the reduced material to produce a nitrided material and subsequently quenching the nitrided material to a martensitic transformation temperature, stress annealing the nitrided material, and magnetic field annealing the stress-annealed material.

Iron-rich permanent magnet

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.

Iron nitride compositions

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.

Iron-based nanoparticles and grains

A permanent magnet may include a FeNphase constitution. In some examples, the permanent magnet may be formed by a technique that includes straining an iron wire or sheet comprising at least one iron crystal in a direction substantially parallel to a &#x3c;001&#x3e; crystal axis of the iron crystal; nitridizing the iron wire or sheet to form a nitridized iron wire or sheet; annealing the nitridized iron wire or sheet to form a FeNphase constitution in at least a portion of the nitridized iron wire or sheet; and pressing the nitridized iron wires and sheets to form bulk permanent magnet.

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.

Electric field switchable magnetic devices

A permanent magnet may include a FeNphase 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 FeNto 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 FeN, 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 FeNphase with preserved strain also is disclosed.

Preservation of strain in iron nitride magnet

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.

Weyl semimetal material for magnetic tunnel junction

Techniques are disclosed for milling an iron-containing raw material in the presence of a nitrogen source to generate anisotropically shaped particles that include iron nitride and have an aspect ratio of at least 1.4. Techniques for nitridizing an anisotropic particle including iron, and annealing an anisotropic particle including iron nitride to form at least one &#x3b1;&#x2033;-FeNphase domain within the anisotropic particle including iron nitride also are disclosed. In addition, techniques for aligning and joining anisotropic particles to form a bulk material including iron nitride, such as a bulk permanent magnet including at least one &#x3b1;&#x2033;-FeNphase domain, are described. Milling apparatuses utilizing elongated bars, an electric field, and a magnetic field also are disclosed.

Iron nitride powder with anisotropic shape

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.

Work function structure for voltage-controlled magnetic anisotropy

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Shoreview, MN, United States of America

Jian-Ping Wang