JP3598171B2 - Exchange spring magnet and method of manufacturing the same - Google Patents
Exchange spring magnet and method of manufacturing the same Download PDFInfo
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- JP3598171B2 JP3598171B2 JP6758496A JP6758496A JP3598171B2 JP 3598171 B2 JP3598171 B2 JP 3598171B2 JP 6758496 A JP6758496 A JP 6758496A JP 6758496 A JP6758496 A JP 6758496A JP 3598171 B2 JP3598171 B2 JP 3598171B2
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- 238000004519 manufacturing process Methods 0.000 title description 6
- 230000005291 magnetic effect Effects 0.000 claims description 56
- 230000005415 magnetization Effects 0.000 claims description 21
- 239000000758 substrate Substances 0.000 claims description 19
- 238000010438 heat treatment Methods 0.000 claims description 11
- 229910020707 Co—Pt Inorganic materials 0.000 claims description 4
- 229910015136 FeMn Inorganic materials 0.000 claims description 4
- 229910003289 NiMn Inorganic materials 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 4
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(II) oxide Inorganic materials [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 claims description 3
- 229910052733 gallium Inorganic materials 0.000 claims description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 3
- GNRSAWUEBMWBQH-UHFFFAOYSA-N nickel(II) oxide Inorganic materials [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 229910052721 tungsten Inorganic materials 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 3
- 229910052715 tantalum Inorganic materials 0.000 claims description 2
- 239000010410 layer Substances 0.000 description 100
- 239000010408 film Substances 0.000 description 66
- 229910001172 neodymium magnet Inorganic materials 0.000 description 35
- 239000000203 mixture Substances 0.000 description 11
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- 238000007254 oxidation reaction Methods 0.000 description 11
- 239000011521 glass Substances 0.000 description 9
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- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
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- 238000010586 diagram Methods 0.000 description 2
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- 238000003475 lamination Methods 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002356 single layer Substances 0.000 description 2
- 229910000521 B alloy Inorganic materials 0.000 description 1
- 230000005290 antiferromagnetic effect Effects 0.000 description 1
- 239000002885 antiferromagnetic material Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F10/00—Thin magnetic films, e.g. of one-domain structure
- H01F10/08—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers
- H01F10/10—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition
- H01F10/12—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition being metals or alloys
- H01F10/126—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition being metals or alloys containing rare earth metals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F10/00—Thin magnetic films, e.g. of one-domain structure
- H01F10/32—Spin-exchange-coupled multilayers, e.g. nanostructured superlattices
- H01F10/3222—Exchange coupled hard/soft multilayers, e.g. CoPt/Co or NiFe/CoSm
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0579—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B with exchange spin coupling between hard and soft nanophases, e.g. nanocomposite spring magnets
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- Hard Magnetic Materials (AREA)
- Thin Magnetic Films (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、小型モータ、磁気センサ、アクチュエータ等に応用されるＲ−ＴＭ−Ｂ系硬磁性層と軟磁性層を積層させた多層構造のＲ−ＴＭ−Ｂ系交換スプリング磁石およびその製造方法に関する。
【０００２】
【従来の技術】
エレクトロニクス機器の小型・軽量化に対応して、永久磁石材料の高性能化が進められている。現在、最高の磁石特性を有するＲ−ＴＭ−Ｂ系磁石の磁気特性を上回る可能性のある材料の一例として、交換スプリング磁石が挙げられる。
交換スプリング磁石は、硬磁性相と軟磁性相の二相からなる超微細結晶組織で構成される永久磁石で、Ｃｏｅｈｏｏｒｎ 等（Ｊ．ｄｅＰｈｙｓ． ｖｏｌ．４９，ｐ６６９（１９８８））や Ｋｎｅｌｌｅｒ 等（ＩＥＥＥ Ｔｒａｎｓ． Ｍａｇ． ｖｏｌ．２７，ｐ３５８８（１９９１））によって提案され、磁化の大きい軟磁性相と保磁力の大きい硬磁性相とを組み合わせ、これらを交換相互作用により磁気的に結合させることで高いエネルギ−積を得ようというものである。
交換スプリング磁石の保磁力は、硬磁性相の磁化が軟磁性相の磁化を固定して、軟磁性相の磁化反転を妨げることによって発現する。十分な保磁力を得るためには、軟磁性相と硬磁性相が強く交換結合していることと、それぞれの相の大きさ（粒径）がナノレベルサイズであることが必要である。この交換スプリング磁石の製造方法は、超急冷法によってアモルファス薄帯を製造し、熱処理によって軟磁性相と硬磁性相が混合した多結晶を得る方法が主流である。
しかしながら、アモルファス薄帯の熱処理によって軟磁性相と硬磁性相とを析出させる交換スプリング磁石の製造方法は、その組織を制御することが極めて難しいという問題がある。
【０００３】
【発明が解決しようとする課題】
本発明は、大きな磁化を持つことで大きな最大エネルギ−積を有するＲ−ＴＭ−Ｂ系交換スプリング磁石およびその製造方法を提供するものである。
【０００４】
【課題を解決するための手段】
交換スプリング磁石において、硬磁性相と交換結合する軟磁性相があると、逆磁界下で軟磁性相から先に磁化反転が始まり、保磁力低下の主要因となる。しかし、軟磁性相のサイズを磁壁幅以下に抑えると、逆磁界下における不均一磁化反転が抑制される。その結果、保磁力は主に硬磁性相の磁気異方性に支配され低下は抑えられる。一方、軟磁性相からより高い磁束密度Ｂを得るためには、軟磁性相の体積比を上げる必要があり、このためには一つの硬磁性相のサイズをできる限り小さくすればよい。硬磁性相のサイズはやはり磁壁幅以下であればよいが、あまり狭いと保磁力を維持するのが困難になるため磁壁幅程度に抑えるのが好ましい。磁壁幅はπ（Ａ／Ｋ）１／２（Ａ：交換スティッフネス定数、Ｋ：磁気異方性エネルギ−）で見積もられるので、軟磁性相をＦｅ、硬磁性相をＮｄ２Ｆｅ１４Ｂとすると、それぞれ６０ｎｍおよび数ｎｍ程度となる。
Ｒ．Ｓｋｏｍｓｋｉ ａｎｄＪ．Ｍ．Ｄ．Ｃｏｅｙ （Ｐｈｙｓ．Ｒｅｖ．Ｂ４８（１９９３）ｐ１５８１２）によると交換スプリング磁石において、最大エネルギ−積（ＢＨ）ｍａｘが最も大きくなるときの硬磁性相の体積比ｆｈは近似的に（１）式で与えられ、このとき最大エネルギ−積は（２）式となる。
【０００５】
Ｓｍ−ＣｏやＮｄ−Ｆｅ−Ｂ磁石の磁気異方性エネルギ−Ｋhは１０7Ｊ／ｍ3 程度であるのに対し、Ｆｅ等の軟磁性体のμ0Ｍs2／４は１０6Ｊ／ｍ3程度であるので、硬磁性相の体積比ｆhは１０％程度あればよいことになる。従って、(ＢＨ)maxは主に軟磁性相の特性に支配され定量的にはμ0Ｍs2／４に僅かな補正が加わる形となる。（２）式においてＮｄ2Ｆｅ14Ｂを硬磁性相、Ｆｅを軟磁性相とした場合には、ｆh＝１０％で、（ＢＨ）max＝０．８ＭＪ／ｍ3（１００ＭＧＯｅ）が期待される。
以上のような特性を得るには、硬磁性相と軟磁性相が接触界面で充分な磁気的結合を有し、それぞれの相厚が上述した磁壁幅程度に制御されている必要がある。本発明者等は、積層膜がこのような制御が最も容易に実現され得る構造であると考えた。また、Ｒ−ＴＭ−Ｂからなる硬磁性層は耐食性が悪く、十分に酸化を抑制しないとＲ2ＴＭ14Ｂが生成しにくくなったり、軟磁性相との交換結合が不十分となって保磁力が劣化する可能性が高いので、本発明者等は、薄膜化による酸化抑制のための保護膜を形成することによって保磁力の低下を防ぐことに想到した。
したがって、本発明のＲ−ＴＭ−Ｂ系交換スプリング磁石は、Ｓ層（磁化の大きさが１．３Ｔ以上である軟磁性層）およびＨ層（１０〜２０ａｔ％のＲ（ＲはＹを含む希土類元素のうちの少なくとも１種）、５〜２０ａｔ％のＢ、残部ＴＭ（ＴＭはＦｅまたはＦｅの一部をＣｏで置換したもの）及び不可避的な不純物を含む硬磁性層）が交互に積層されており、前記Ｓ層およびＨ層を積層した多層膜の最外面にＭ層（Ｍ層はＣｒ，Ｔｉ，Ｗ，Ｃｕ，Ｔａ，ＦｅＭｎ，ＮｉＭｎ，ＮｉＯ，ＦｅＯ，ＣｏＯ，Ｃｏ−Ｐｔ，Ｆｅ−Ｐｔのうちの１種または２種以上からなる層）を有することを特徴とする。
【０００７】
本発明において、Ｓ層とＨ層とを交換結合させるために、Ｓ層とＨ層を交互に積層して多層膜とすることが望ましい。また、Ｓ層およびＨ層を積層した多層膜の最外面にＭ層（Ｃｒ，Ｔｉ，Ｗ，Ｃｕ，Ｔａ，ＦｅＭｎ，ＮｉＭｎ，ＮｉＯ，ＦｅＯ，ＣｏＯ，Ｃｏ−Ｐｔ，Ｆｅ−Ｐｔのうちの１種または２種以上からなる層）を形成し、Ｓ層とＨ層の酸化を抑制することが望ましい。
【０００８】
本発明において、Ｈ層は、１０〜２０ａｔ％のＲ（ＲはＹを含む希土類元素のうちの少なくとも１種）、５〜２０ａｔ％のＢ、残部ＴＭ（ＴＭはＦｅまたはＦｅの一部をＣｏで置換したもの）及び不可避的な不純物を含む硬磁性層である。Ｒとしては、特にＮｄまたはＰｒを含むことが望ましく、ＮｄまたはＰｒの一部をＤｙで置換してもよい。Ｒ−ＴＭ−ＢからなるＨ層は、Ｒ2ＴＭ14Ｂ相を含み、膜厚が５〜１００ｎｍであることが望ましい。
Ｈ層のＲが１０ａｔ％未満では十分な保磁力が発現せず、２０ａｔ％超ではＦｅ成分が減少して（ＢＨ）ｍａｘとＢｒが減少する。Ｂは５ａｔ％未満では保磁力が低下し、２０ａｔ％超では（ＢＨ）ｍａｘとＢｒが低下する。また、Ｈ層にＣｒ、Ｎｂ、Ａｌ、Ｇａ、Ｚｎ、Ｃｕのうちの少なくとも１種の元素を添加すると、更に保磁力と角型性の良いＲ−ＴＭ−Ｂ系交換スプリング磁石を得ることができるが、４ａｔ％を超えて添加すると（ＢＨ）ｍａｘとＢｒが低下するので、添加量を０．５〜４ａｔ％とする。
【０００９】
Ｒ−ＴＭ−ＢからなるＨ層の磁化は室温で通常１．３Ｔ以上であるので、交換スプリング磁石の優位性を得るためには、Ｓ層の磁化の大きさは室温で１．３Ｔ以上とし、更にバルクのＲ−ＴＭ−Ｂ系磁石の特性を上回るには、１．５Ｔ以上とするのが望ましい。室温における磁化の大きさが１．３Ｔ以上の軟磁性材料としては、Ｆｅ：２Ｔ，Ｆｅ−Ｃｏ：２．３Ｔ，Ｆｅ−Ｎ：２．４Ｔ等がある。Ｓ層は、その磁壁の幅から考えて、５ｎｍ〜５００ｎｍの範囲の膜厚を有することが望ましい。
Ｈ層とＳ層を交換結合させるために、Ｓ層とＨ層を交互に積層した多層膜を形成するが、積層順はＳ層、Ｈ層、Ｓ層、・・・Ｓ層と積層しても、Ｈ層、Ｓ層、Ｈ層、・・・Ｈ層と積層しても、Ｓ層、Ｈ層、Ｓ層、・・・Ｈ層と積層しても、Ｈ層、Ｓ層、Ｈ層、・・・Ｓ層と積層してもいづれでもよい。
【００１０】
Ｓ層とＨ層を交互に積層した多層膜の最外面にＭ層を形成し、Ｓ層とＨ層の酸化を制御する。Ｍ層は、最外面全面に形成してもよいし、多層膜を挟むように、または片方に形成してもよい。Ｍ層は、基板と多層膜との間、およびＳ層とＨ層との多層膜上のいづれか一方に形成することによっても酸化制御の効果は得られるが、最外面全面あるいは多層膜を挟むように形成することによりＳ層とＨ層の酸化を十分制御することができ、その結果、Ｈ層とＳ層の交換結合が強くなり、磁性特性の優れた多層膜を得ることができる。また、基板上にＭ層を成膜し、その上にＳ層とＨ層の多層膜を積層することによって、Ｓ層またはＨ層の酸化制御および基板との反応を防ぐという効果が得られる。
Ｍ層の厚さは、これと隣接するＨ層あるいはＳ層との相互拡散により界面で合金あるいは化合物を形成しても充分にその機能を損なうことのないように５ｎｍ〜１００ｎｍ、望ましくは５〜２０ｎｍとする。
【００１１】
ＮｉＯ，ＦｅＯ，ＣｏＯは反強磁性絶縁体であるため、これをＭ層として用いれば、酸化抑制の効果に加え、磁化反転を抑えることで保磁力向上の効果を得ることができる。ＦｅＭｎ，ＮｉＭｎも反強磁性体であるためこれをＭ層として用いれば、保磁力向上の効果を得ることができるが、他のＭ層構成物質に比し酸化防止効果が少ないので、基板とＨ層またはＳ層との間に形成することが望ましい。また、Ｃｏ−Ｐｔ，ＦｅーＰｔは強い結晶磁気異方性を有する強磁性金属であるため、これをＭ層として用いれば酸化防止効果と保磁力増大の効果に加えて磁化の増大も期待できる。
【００１２】
Ｈ層の成膜時の酸化を抑制するため、Ｈ層は室温の基板温度で成膜することが好ましいが、その場合Ｒ−ＴＭ−ＢからなるＨ層はＲ2ＴＭ14Ｂは結晶化せずにアモルファスとなっており保磁力が発現しない。この場合、Ｒ2ＴＭ14Ｂの多結晶を得るために熱処理が必要である。熱処理温度は７７３ Ｋ（５００℃）未満にするとＲ2ＴＭ14Ｂが結晶化しないので保磁力が発現せず、１０７３Ｋ（８００℃）を超えると保磁力が急激に減少する。したがって、熱処理温度は７７３Ｋ（５００℃）から１０７３Ｋ（８００℃）が適当であるが、熱処理中の拡散による積層構造の乱れが少なく、かつＲ2ＴＭ14Ｂが十分生成する、７７３Ｋ（５５０℃）から９２３Ｋ（６５０℃）が望ましい。
【００１３】
【発明の実施の態様】
（実施例１）
二極マグネトロンスパッタ装置の真空槽内を８×１０−４Ｐａ以下に排気し、Ａｒガスを導入して８×１０−１Ｐａとし、請求項１に記載したＨ層の膜組成になるようなＮｄ−Ｆｅ−Ｂ合金ターゲットに高周波電圧を印加して室温のガラス基板上に成膜した。投入電力は２００Ｗとし、基板とターゲットの間に取り付けたシャッターを閉じた状態で２０分間予備スパッタリングを行ってターゲット表面上の酸化物等を除去した後、シャッターを開けてＮｄ−Ｆｅ−Ｂ膜を２０ｎｍ成膜した。Ｎｄ−Ｆｅ−Ｂ膜単層の膜組成はＮｄ１３〜１５ＦｅｂａｌＢ７〜１１（ａｔ％）、成膜速度は２．０μｍ／ｈｏｕｒである。引き続いて真空を破らずに、Ｆｅターゲットに高周波電圧を印加してＮｄ−Ｆｅ−Ｂと同様の成膜条件でＦｅ膜を２０ｎｍ成膜した。成膜速度は０．３μｍ／ｈｏｕｒである。これを交互に繰り返すことによってＮｄ−Ｆｅ−ＢとＦｅの多層膜を作製し（積層周期５）、最後にＮｄ−Ｆｅ−Ｂ膜を成膜した。得られたＮｄ−Ｆｅ−Ｂ／Ｆｅ多層膜を８７３Ｋ（６００℃）で３０分間、３×１０−３Ｐａ以下の真空中で熱処理した。
【００１４】
（実施例２）
ガラス基板上にＴｉを２０ｎｍ成膜し、次に実施例１と同様のＮｄ−Ｆｅ−Ｂ／Ｆｅ多層膜を成膜し、最後にＴｉを２０ｎｍ成膜して図１のようなＴｉ／（Ｎｄ−Ｆｅ−Ｂ／Ｆｅ）５／Ｎｄ−Ｆｅ−Ｂ／Ｔｉ積層膜とした。Ｔｉの成膜条件はＦｅ、Ｎｄ−Ｆｅ−Ｂと同一で成膜速度は１．３μｍ／ｈｏｕｒである。得られた膜は（実施例１）と同条件で熱処理した。
【００１５】
（実施例３）
ガラス基板上に（実施例１）と同様のＮｄ−Ｆｅ−Ｂ／Ｆｅ多層膜を成膜し、最後にＴｉを２０ｎｍ成膜した。つまり、（実施例２）と比較してガラス基板とＮｄ−Ｆｅ−Ｂ／Ｆｅ多層膜の間のＴｉ層がない膜を作製した。得られた膜は（実施例１）と同条件で熱処理した。
【００１６】
（実施例４）
ガラス基板上にＴｉを２０ｎｍ成膜し、引き続いて（実施例１）と同様のＮｄ−Ｆｅ−Ｂ／Ｆｅ多層膜を成膜した。すなわち、（実施例２）と比較してＮｄ−Ｆｅ−Ｂ／Ｆｅ多層膜上のＴｉ層がない膜を作製した。得られた膜は（実施例１）と同条件で熱処理した。
【００１７】
実施例１〜４で得られた膜の減磁曲線を図２に示す。最も保磁力が大きいのは実施例２である。実施例１は、Ｎｄ−Ｆｅ−Ｂ層の酸化により保磁力が発現しなかったと考えられる。実施例３、４は実施例１より保磁力が大きいが、実施例２と比較するとやや保磁力が低下する。これらの結果から、Ｎｄ−Ｆｅ−Ｂ／Ｆｅ多層膜は、Ｔｉ等の保護層が基板と多層膜の間または多層膜の表面（最上部）の少なくとも一方に必要で、望ましくは、Ｔｉ等の保護層が基板と多層膜の間かつ多層膜の表面（最上部）に必要であることがわかる。
実施例１および２で得られた膜のスプリングバック特性を調べるため、減磁界の印加と減磁界の除去を繰り返した場合のマイナーループを、図５、図６に示す。図５からは、実施例１で得られた膜の磁化のスプリングバックは認められなかった。一方、図６を見ると、実施例２で得られた膜は、減磁界を印加しても磁化がリコイルする磁化のスプリングバックが認められたことから、Ｈ層とＳ層が交換結合した交換スプリング磁石であることが確認できた。このことから、Ｈ層とＳ層とを交換結合させるためには、Ｔｉ等の保護層を形成することが有効であると考えられる。
【００１８】
（実施例５）実施例２のＴｉ／（Ｎｄ−Ｆｅ−Ｂ／Ｆｅ）5／Ｎｄ−Ｆｅ−Ｂ／Ｔｉ積層膜において、熱処理温度を６７３Ｋから１１２３Ｋ（４００℃から８５０℃）の範囲で変化させた。図３に保磁力の熱処理温度依存性を示す。熱処理温度７７３Ｋ（５００℃）未満では充分な保磁力が発現せず、１０７３Ｋ（８００℃）を超えると基板の変形、急速な特性の劣化を招く。従って、熱処理温度は７７３Ｋから１０７３Ｋ（５００℃から８００℃）の範囲であることが必要で、更に、保磁力の大きい８２３Ｋから９２３Ｋ（５５０℃から６５０℃）の範囲が望ましい。
【００１９】
（実施例６）
Ｃｒを含んだＮｄ−Ｆｅ−Ｂ合金ターゲットを用い、その他の条件は実施例２と同様の方法でＣｒ／（Ｎｄ−Ｆｅ−Ｃｒ−Ｂ／Ｆｅ）５／Ｎｄ−Ｆｅ−Ｃｒ−Ｂ／Ｃｒ積層膜を作製した（Ｎｄ−Ｆｅ−Ｃｒ−Ｂ膜単層の膜組成はＮｄ１３〜１５ＦｅｂａｌＢ７〜１１Ｃｒ０．５〜１．５（ａｔ％）である）。得られた膜は（実施例１）と同様に熱処理した。減磁曲線を（実施例２）と比較して図４に示す。Ｎｄ−Ｆｅ−Ｂ層にＣｒを添加した場合の方が保磁力と角型性の良い薄膜磁石を得ることができる。この効果は、Ｎｂ、Ａｌ、Ｇａ、Ｚｎ、Ｃｕの場合でも同様であった。
【００２０】
（実施例７）
ガラス基板上に、表１に示すＭ層を１５ｎｍ成膜し、次に膜組成を表１に示す膜組成とした以外は実施例１と同様の条件で（Ｎｄ−Ｆｅ−Ｂ／Ｓ）５／Ｎｄ−Ｆｅ−Ｂを成膜し、さらに表１に示すＭ層を１５ｎｍ成膜した。Ｎｄ−Ｆｅ−Ｂ層の厚さ、Ｓ層の厚さは、それぞれ１５ｎｍ、５０ｎｍとした。得られた積層膜を５７０℃〜６００℃で３０分間、３×１０−３Ｐａ以下の真空中で熱処理した。得られた磁石の磁気特性を表１に示す。
【００２１】
【表１】
（実施例８）
ガラス基板上に、表２に示すＭ層を１５ｎｍ成膜し、次に膜組成を表１に示す膜組成とした以外は実施例１と同様の条件で（Ｎｄ−Ｆｅ−Ｂ／Ｆｅ）５／Ｎｄ−Ｆｅ−Ｂを成膜し、さらに表２に示すＭ層を１５ｎｍ成膜した。Ｎｄ−Ｆｅ−Ｂ層の厚さ、Ｓ層の厚さは、それぞれ１５ｎｍ、５０ｎｍとした。得られた積層膜を６００℃〜６２０℃で３０分間、３×１０−３Ｐａ以下の真空中で熱処理した。得られた磁石の磁気特性を表２に示す。
【００２３】
【表２】
（実施例９）
ガラス基板上に、表３に示すＭ層を１５ｎｍ成膜し、次に膜組成を表１に示す膜組成とした以外は実施例１と同様の条件で（Ｎｄ−Ｆｅ−Ｂ／Ｆｅ）５／Ｎｄ−Ｆｅ−Ｂを成膜し、さらに表３に示すＭ層を２０ｎｍ成膜した。Ｎｄ−Ｆｅ−Ｂ層の厚さ、Ｓ層の厚さは、それぞれ１５ｎｍおよび５０ｎｍとした。得られた積層膜を５７０℃〜６００℃で３０分間、３×１０−３Ｐａ以下の真空中で熱処理した。得られた磁石の磁気特性を表３に示す。
【００２５】
【表３】
（実施例１０）
ガラス基板上に、表４に示すＭ層を１５ｎｍ成膜し、次に膜組成を表１に示す膜組成とした以外は実施例１と同様の条件で（Ｎｄ−Ｆｅ−Ｂ／Ｆｅ）５／Ｎｄ−Ｆｅ−Ｂを成膜し、さらに表４に示すＭ層を１５ｎｍ成膜した。Ｎｄ−Ｆｅ−Ｂ層の厚さ、Ｓ層の厚さは、それぞれ１５ｎｍおよび５０ｎｍとした。得られた積層膜を５７０℃〜６００℃で３０分間、３×１０−３Ｐａ以下の真空中で熱処理した。得られた磁石の磁気特性を表４に示す。
【００２７】
【表４】
本発明により、磁化が大きく、大きな最大エネルギー積を有するＲ−ＴＭ−Ｂ系交換スプリング磁石が得られる。
【図面の簡単な説明】
【図１】本発明交換スプリング磁石の断面模式図である。
【図２】Ｍ層と減磁曲線の関係を示す図である。
【図３】保磁力の熱処理温度依存性を表す図である。
【図４】Ｈ層にＣｒ添加した場合の減磁曲線である。
【図５】磁化のスプリングバックを示さないマイナーループである。
【図６】磁化のスプリングバックを示すマイナーループである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an R-TM-B -based exchange spring magnet having a multilayer structure in which an R-TM-B-based hard magnetic layer and a soft magnetic layer applied to a small motor, a magnetic sensor, an actuator, and the like, and a method of manufacturing the same. .
[0002]
[Prior art]
Permanent magnet materials have been improved in performance in response to miniaturization and weight reduction of electronic devices. At present, an exchange spring magnet is an example of a material that may exceed the magnetic properties of the R-TM-B-based magnet having the highest magnet properties.
The exchange spring magnet is a permanent magnet composed of an ultrafine crystal structure composed of two phases, a hard magnetic phase and a soft magnetic phase, and is described in Coehorn et al. (J. dePhys. Vol. 49, p669 (1988)) and Kneller et al. (IEEE). Trans. Mag. Vol.27, p3588 (1991)), which combines a soft magnetic phase with a large magnetization and a hard magnetic phase with a large coercive force, and magnetically couples them by exchange interaction to achieve high energy. -To get the product.
The coercive force of the exchange spring magnet is generated by the magnetization of the hard magnetic phase fixing the magnetization of the soft magnetic phase and preventing the magnetization reversal of the soft magnetic phase. In order to obtain a sufficient coercive force, it is necessary that the soft magnetic phase and the hard magnetic phase are strongly exchange-coupled and that the size (particle size) of each phase is a nano-level size. The mainstream of the manufacturing method of this exchange spring magnet is a method of manufacturing an amorphous ribbon by a rapid quenching method and obtaining a polycrystal in which a soft magnetic phase and a hard magnetic phase are mixed by a heat treatment.
However, the method of manufacturing an exchange spring magnet that precipitates a soft magnetic phase and a hard magnetic phase by heat treatment of an amorphous ribbon has a problem that it is extremely difficult to control the structure.
[0003]
[Problems to be solved by the invention]
The present invention provides an R-TM-B-based exchange spring magnet having a large maximum energy product by having a large magnetization and a method of manufacturing the same.
[0004]
[Means for Solving the Problems]
In the exchange spring magnet, if there is a soft magnetic phase exchange-coupled with the hard magnetic phase, the magnetization reversal starts from the soft magnetic phase under the reverse magnetic field, which is a main factor of the decrease in coercive force. However, if the size of the soft magnetic phase is suppressed to the domain wall width or less, non-uniform magnetization reversal under a reverse magnetic field is suppressed. As a result, the coercive force is mainly governed by the magnetic anisotropy of the hard magnetic phase, and the decrease is suppressed. On the other hand, in order to obtain a higher magnetic flux density B from the soft magnetic phase, it is necessary to increase the volume ratio of the soft magnetic phase. To this end, the size of one hard magnetic phase may be reduced as much as possible. The size of the hard magnetic phase may be smaller than the domain wall width, but if it is too narrow, it becomes difficult to maintain the coercive force. Since the domain wall width is estimated by π (A / K) 1/2 (A: exchange stiffness constant, K: magnetic anisotropy energy), if the soft magnetic phase is Fe and the hard magnetic phase is Nd2Fe14B, each is 60 nm. And several nm.
R. Skomski and J.J. M. D. According to Coey (Phys. Rev. B48 (1993) p15812), in the exchange spring magnet, the volume ratio fh of the hard magnetic phase when the maximum energy-product (BH) max is maximized is approximately given by equation (1). At this time, the maximum energy product is given by equation (2).
[0005]
The magnetic anisotropy energy Kh of a Sm-Co or Nd-Fe-B magnet is about 10 7 J / m 3, while the
In order to obtain the above characteristics, it is necessary that the hard magnetic phase and the soft magnetic phase have a sufficient magnetic coupling at the contact interface, and the thickness of each phase is controlled to the above-mentioned domain wall width. The present inventors have considered that the laminated film has such a structure that such control can be most easily realized. Further, the hard magnetic layer made of R-TM-B has poor corrosion resistance, and if the oxidation is not sufficiently suppressed, it is difficult to form R2TM14B, or the exchange coupling with the soft magnetic phase becomes insufficient and the coercive force is deteriorated. Since the possibility is high, the present inventors have conceived of preventing a decrease in coercive force by forming a protective film for suppressing oxidation due to thinning.
Therefore, the R-TM-B-based exchange spring magnet of the present invention has an S layer (a soft magnetic layer having a magnetization magnitude of 1.3 T or more) and an H layer (10 to 20 at% of R (R includes Y). At least one of the rare earth elements), 5 to 20 at% of B, the balance TM (TM is Fe or a part of Fe replaced with Co), and a hard magnetic layer containing unavoidable impurities) are alternately laminated. An M layer (M layer is Cr, Ti, W, Cu, Ta, FeMn, NiMn, NiO, FeO, CoO, Co-Pt, Fe) is formed on the outermost surface of the multilayer film in which the S layer and the H layer are stacked. -Pt).
[0007]
In the present invention, in order to exchange-couple the S layer and the H layer, it is preferable that the S layer and the H layer are alternately stacked to form a multilayer film. Further, M layer on the outermost surface of the multilayer film formed by laminating S layer and H layer (Cr, Ti, W, Cu , Ta, FeMn, NiMn, NiO, FeO, CoO, of Co-Pt, Fe-Pt 1 It is desirable to form a seed or a layer composed of two or more kinds and suppress the oxidation of the S layer and the H layer.
[0008]
In the present invention, H layer, 10 to 20 at% of R (R is at least one of rare earth elements including Y), 5 to 20 at% of B, and part of the remainder TM (TM is Fe or Fe Co And a hard magnetic layer containing unavoidable impurities. The R, particularly desirably containing Nd or Pr, for part of Nd or Pr may be replaced with Dy. It is desirable that the H layer composed of R-TM-B contains the R2TM14B phase and has a thickness of 5 to 100 nm.
R H layer is not expressed in sufficient coercivity less than 10at%, 20at% ultra the Fe component is reduced (BH) max and Br is reduced. B is lowered 5at% less than the coercive force, the 20at% Ultra (BH) max and Br is lowered. Further, Cr in H layer, Nb, Al, Ga, Zn , the addition of at least one element of Cu, it is possible to obtain a better R-TM-B based exchange-spring magnet having the coercive force and squareness Although it is possible, if added in excess of 4 at%, (BH) max and Br decrease, so the addition amount is 0.5 to 4 at% .
[0009]
Since the magnetization of the H layer made of R-TM-B is usually 1.3 T or more at room temperature, in order to obtain the advantage of the exchange spring magnet, the magnitude of the magnetization of the S layer should be 1.3 T or more at room temperature. In order to further exceed the characteristics of the bulk R-TM-B magnet, it is desirable to set it to 1.5T or more. Examples of soft magnetic materials having a magnetization magnitude of 1.3 T or more at room temperature include Fe: 2T, Fe-Co: 2.3 T, and Fe-N: 2.4 T. Considering the width of the domain wall, the S layer preferably has a thickness in the range of 5 nm to 500 nm.
In order to exchange-couple the H layer and the S layer, a multilayer film in which the S layer and the H layer are alternately laminated is formed, and the lamination order is S layer, H layer, S layer,. , H layer, S layer, H layer,... H layer, or S layer, H layer, S layer,. ,... May be laminated with the S layer.
[0010]
An M layer is formed on the outermost surface of the multilayer film in which the S layer and the H layer are alternately stacked, and the oxidation of the S layer and the H layer is controlled. The M layer may be formed on the entire outermost surface, or may be formed so as to sandwich a multilayer film or on one side. The effect of controlling oxidation can be obtained by forming the M layer between the substrate and the multilayer film and / or the S layer and the H layer on the multilayer film. oxidation of the S layer and the H layer can be sufficiently controlled by the arc formed, as a result, the exchange coupling of the H layer and S layer becomes strong, it is possible to obtain an excellent multi-layer film of the magnetic properties. Further, by forming an M layer on the substrate and laminating a multilayer film of the S layer and the H layer on the M layer, the effect of controlling the oxidation of the S layer or the H layer and preventing the reaction with the substrate can be obtained.
The thickness of the M layer is from 5 nm to 100 nm, preferably from 5 nm to 100 nm, so that even if an alloy or compound is formed at the interface by interdiffusion with the adjacent H layer or S layer, its function is not sufficiently impaired. 20 nm.
[0011]
Since NiO, FeO, and CoO are antiferromagnetic insulators, if they are used as the M layer, in addition to the effect of suppressing oxidation, the effect of improving coercive force can be obtained by suppressing magnetization reversal. Since FeMn and NiMn are also antiferromagnetic materials, if they are used as the M layer, the effect of improving the coercive force can be obtained. It is desirable to form between the layer and the S layer. Further, since Co-Pt and Fe-Pt are ferromagnetic metals having strong crystal magnetic anisotropy, if they are used as the M layer, an increase in magnetization can be expected in addition to an effect of preventing oxidation and an increase in coercive force. .
[0012]
In order to suppress oxidation during the formation of the H layer, the H layer is preferably formed at a substrate temperature of room temperature. In this case, the H layer composed of R-TM-B becomes amorphous without crystallization of R2TM14B. The coercive force does not appear. In this case, heat treatment is required to obtain R2TM14B polycrystal. The heat treatment temperature is so R2TM14B When less than 773 K (500 ℃) does not crystallize without coercive force expressed, 1073K (800 ℃) exceeds the coercive force rapidly decreases. Therefore, the heat treatment temperature is preferably from 773 K (500 ° C.) to 1073 K (800 ° C.). ° C) is desirable.
[0013]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(Example 1)
The inside of the vacuum chamber of the bipolar magnetron sputtering apparatus is evacuated to 8 × 10 −4 Pa or less, and Ar gas is introduced to 8 × 10 −1 Pa, so that the Nd− has a film composition of the H layer according to claim 1. A high frequency voltage was applied to the Fe-B alloy target to form a film on a glass substrate at room temperature. The input power was 200 W, and after pre-sputtering was performed for 20 minutes with the shutter attached between the substrate and the target closed to remove oxides and the like on the target surface, the shutter was opened to remove the Nd-Fe-B film. A 20 nm film was formed. The film composition of the single layer of the Nd-Fe-B film is Nd13-15 FebalB7-11 (at%), and the film formation rate is 2.0 μm / hour. Subsequently, a high-frequency voltage was applied to the Fe target without breaking the vacuum, and a 20 nm-thick Fe film was formed under the same film forming conditions as those for Nd-Fe-B. The deposition rate is 0.3 μm / hour. By repeating this alternately, a multilayer film of Nd—Fe—B and Fe was produced (lamination cycle 5), and finally a Nd—Fe—B film was formed. The obtained Nd—Fe—B / Fe multilayer film was heat-treated at 873 K (600 ° C.) for 30 minutes in a vacuum of 3 × 10 −3 Pa or less.
[0014]
(Example 2)
A 20 nm Ti film is formed on a glass substrate, then an Nd—Fe—B / Fe multilayer film is formed as in Example 1, and a 20 nm Ti film is formed. (Nd-Fe-B / Fe) 5 / Nd-Fe-B / Ti laminated film. The film forming conditions for Ti are the same as those for Fe and Nd—Fe—B, and the film forming speed is 1.3 μm / hour. The obtained film was heat-treated under the same conditions as in (Example 1).
[0015]
(Example 3)
An Nd-Fe-B / Fe multilayer film similar to that of (Example 1) was formed on a glass substrate, and finally a Ti film was formed to a thickness of 20 nm. That is, a film having no Ti layer between the glass substrate and the Nd-Fe-B / Fe multilayer film was manufactured as compared with (Example 2). The obtained film was heat-treated under the same conditions as in (Example 1).
[0016]
(Example 4)
20 nm of Ti was formed on a glass substrate, and subsequently, an Nd-Fe-B / Fe multilayer film similar to that of (Example 1) was formed. That is, a film having no Ti layer on the Nd-Fe-B / Fe multilayer film was manufactured as compared with (Example 2). The obtained film was heat-treated under the same conditions as in (Example 1).
[0017]
FIG. 2 shows demagnetization curves of the films obtained in Examples 1 to 4. Example 2 has the largest coercive force. In Example 1, it is considered that the coercive force did not appear due to the oxidation of the Nd-Fe-B layer. Examples 3 and 4 have a larger coercive force than Example 1, but have a slightly lower coercive force compared to Example 2. From these results, the Nd—Fe—B / Fe multilayer film requires a protective layer such as Ti between the substrate and the multilayer film or at least one of the surfaces (uppermost portion) of the multilayer film. It can be seen that a protective layer is required between the substrate and the multilayer film and on the surface (uppermost portion) of the multilayer film.
FIGS. 5 and 6 show minor loops when the application of the demagnetizing field and the removal of the demagnetizing field are repeated in order to examine the springback characteristics of the films obtained in Examples 1 and 2. From FIG. 5, no springback of the magnetization of the film obtained in Example 1 was observed. On the other hand, referring to FIG. 6, the film obtained in Example 2 showed a magnetization springback in which the magnetization was recoiled even when a demagnetizing field was applied. It was confirmed that it was a spring magnet. From this fact, it is considered effective to form a protective layer of Ti or the like in order to exchange-couple the H layer and the S layer.
[0018]
(Example 5) In the Ti / (Nd-Fe-B / Fe) 5 / Nd-Fe-B / Ti laminated film of Example 2, the heat treatment temperature was changed in the range of 673K to 1123K (400 ° C to 850 ° C). I let it. FIG. 3 shows the dependence of the coercive force on the heat treatment temperature. If the heat treatment temperature is lower than 773 K (500 ° C.), a sufficient coercive force is not exhibited, and if it exceeds 1073 K (800 ° C.), deformation of the substrate and rapid deterioration of characteristics are caused. Therefore, the heat treatment temperature needs to be in the range of 773 K to 1073 K (500 ° C. to 800 ° C.), and more preferably in the range of 823 K to 923 K (550 ° C. to 650 ° C.) having a large coercive force.
[0019]
(Example 6)
A Cr / (Nd-Fe-Cr-B / Fe) 5 / Nd-Fe-Cr-B / Cr was used in the same manner as in Example 2 except that an Nd-Fe-B alloy target containing Cr was used. A laminated film was prepared (the film composition of the single layer of the Nd-Fe-Cr-B film was Nd13-15 FebalB7-11Cr 0.5-1.5 (at%)). The obtained film was heat-treated in the same manner as in (Example 1). FIG. 4 shows the demagnetization curve in comparison with (Example 2). When Cr is added to the Nd-Fe-B layer, a thin film magnet having better coercive force and squareness can be obtained. This effect was similar in the case of Nb, Al, Ga, Zn, and Cu.
[0020]
(Example 7)
On the glass substrate, an M layer shown in Table 1 was formed to a thickness of 15 nm, and then the film composition was changed to the film composition shown in Table 1 under the same conditions as in Example 1 (Nd-Fe-B / S) 5. / Nd-Fe-B, and an M layer shown in Table 1 was formed to a thickness of 15 nm. The thickness of the Nd-Fe-B layer and the thickness of the S layer were 15 nm and 50 nm, respectively. The obtained laminated film was heat-treated at 570 ° C. to 600 ° C. for 30 minutes in a vacuum of 3 × 10 −3 Pa or less. Table 1 shows the magnetic properties of the obtained magnet.
[0021]
[Table 1]
(Example 8)
On the glass substrate, an M layer shown in Table 2 was formed to a thickness of 15 nm, and then the film composition was changed to the film composition shown in Table 1 under the same conditions as in Example 1 except that (Nd-Fe-B / Fe) 5 / Nd-Fe-B, and an M layer shown in Table 2 having a thickness of 15 nm. The thickness of the Nd-Fe-B layer and the thickness of the S layer were 15 nm and 50 nm, respectively. The obtained laminated film was heat-treated at 600 to 620 ° C. for 30 minutes in a vacuum of 3 × 10 −3 Pa or less. Table 2 shows the magnetic properties of the obtained magnet.
[0023]
[Table 2]
(Example 9)
On a glass substrate, an M layer shown in Table 3 was formed to a thickness of 15 nm, and then the film composition was changed to the film composition shown in Table 1 under the same conditions as in Example 1 (Nd-Fe-B / Fe) 5. / Nd-Fe-B, and an M layer shown in Table 3 having a thickness of 20 nm. The thickness of the Nd-Fe-B layer and the thickness of the S layer were 15 nm and 50 nm, respectively. The obtained laminated film was heat-treated at 570 ° C. to 600 ° C. for 30 minutes in a vacuum of 3 × 10 −3 Pa or less. Table 3 shows the magnetic properties of the obtained magnet.
[0025]
[Table 3]
(Example 10)
On a glass substrate, an M layer shown in Table 4 was deposited to a thickness of 15 nm, and then the film composition was changed to the film composition shown in Table 1 under the same conditions as in Example 1 except that (Nd-Fe-B / Fe) 5 / Nd-Fe-B, and an M layer shown in Table 4 was formed to a thickness of 15 nm. The thickness of the Nd-Fe-B layer and the thickness of the S layer were 15 nm and 50 nm, respectively. The obtained laminated film was heat-treated at 570 ° C. to 600 ° C. for 30 minutes in a vacuum of 3 × 10 −3 Pa or less. Table 4 shows the magnetic properties of the obtained magnet.
[0027]
[Table 4]
According to the present invention, an R-TM-B exchange spring magnet having a large magnetization and a large maximum energy product can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an exchange spring magnet of the present invention.
FIG. 2 is a diagram showing a relationship between an M layer and a demagnetization curve.
FIG. 3 is a diagram showing the dependence of coercivity on heat treatment temperature.
FIG. 4 is a demagnetization curve when Cr is added to the H layer.
FIG. 5 is a minor loop showing no magnetization springback.
FIG. 6 is a minor loop showing magnetization springback.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6758496A JP3598171B2 (en) | 1995-12-27 | 1996-03-25 | Exchange spring magnet and method of manufacturing the same |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34088295 | 1995-12-27 | ||
| JP7-340882 | 1995-12-27 | ||
| JP6758496A JP3598171B2 (en) | 1995-12-27 | 1996-03-25 | Exchange spring magnet and method of manufacturing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09237714A JPH09237714A (en) | 1997-09-09 |
| JP3598171B2 true JP3598171B2 (en) | 2004-12-08 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP6758496A Expired - Lifetime JP3598171B2 (en) | 1995-12-27 | 1996-03-25 | Exchange spring magnet and method of manufacturing the same |
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| JP (1) | JP3598171B2 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002015206A1 (en) * | 2000-08-02 | 2002-02-21 | Sumitomo Special Metals Co., Ltd. | Thin film rare earth permanent magnet, and method for manufacturing the permanent magnet |
| JP2002270418A (en) | 2001-03-09 | 2002-09-20 | Matsushita Electric Ind Co Ltd | Rare earth thick film magnet manufacturing method and magnet motor using rare earth thick film magnet manufactured through the above method |
| JP4422953B2 (en) | 2002-08-22 | 2010-03-03 | 株式会社日立製作所 | Method for manufacturing permanent magnet |
| JP4654409B2 (en) * | 2004-12-13 | 2011-03-23 | 独立行政法人物質・材料研究機構 | Manufacturing method of nanocomposite magnet |
| WO2006109615A1 (en) * | 2005-04-05 | 2006-10-19 | Namiki Seimitsu Houseki Kabushiki Kaisha | Stacked permanent magnet |
| WO2007119271A1 (en) * | 2006-03-20 | 2007-10-25 | Namiki Seimitsu Houseki Kabushiki Kaisha | Thin-film rare earth magnet and method for manufacturing the same |
| ITTO20080462A1 (en) * | 2008-06-13 | 2009-12-14 | Torino Politecnico | METHOD FOR THE PRODUCTION OF NANOSTRUCTURED MACROSCOPIC MAGNETS WITH HIGH DENSITY OF MAGNETIC ENERGY AND RELATED MAGNETS |
| JP5327433B2 (en) * | 2008-08-22 | 2013-10-30 | ミネベア株式会社 | Method for manufacturing rotor magnet of micro rotating electric machine |
| JP5390996B2 (en) * | 2009-08-28 | 2014-01-15 | 株式会社豊田中央研究所 | Rare earth highly oriented magnetic thin film and manufacturing method thereof, porcelain member and rare earth permanent magnet |
| FR3025357A1 (en) * | 2014-09-01 | 2016-03-04 | Vivier Harry J P | PERMANENT MAGNETS STRUCTURES IN STRATES |
| JPWO2022045260A1 (en) * | 2020-08-27 | 2022-03-03 |
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