Coercivity engineering in Sm(Fe0.8Co0.2)12B0.5 thin films by Si grain boundary diffusion

Bolyachkin, A.; Sepehri-Amin, H.; Kambayashi, M.; Mori, Yoichi; Ohkubo, T.; Takahashi, Y. K.; Shima, T.; Hara, Kazuhiro

doi:10.1016/j.actamat.2022.117716

Cited by 18 publications

(7 citation statements)

References 26 publications

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“…解析などの巨視的な解析手法に加え [20][21][22] ，最近では磁気トモグラフィー測定による微視的な解析手法も整備されつつある [23][24][25] ．また，Micromagnetic (MM) シミュレーションも大きな進展を見せており [26][27][28][29][30][31] ，計算機や計算アルゴリズムの進化に加えて機械学習を導入した高速化，大規模化 [32][33][34] や電子顕微鏡で得た実際の微細組織構造をモデリングする手法の開発 [35][36][37] なども進められている． ÁEðM; HÞ ¼ EðM [20][21][22]62)…”

Section: はじめにunclassified

Recent Unrevealing on Magnetic Hysteresis of Permanent Magnets

Okamoto

2023

J. Japan Inst. Metals and Materials

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Magnetic hysteresis and coercivity mechanism of a permanent magnet have been long discussed, and their understandings have been significantly deepened during the last decade. Magnetization reversal in a permanent magnet proceeds with thermally activated nucleation and domain wall depinning processes followed by magnetic domain expansions. To treat theoretically the thermally activated magnetization reversal process, atomistic spin model and continuum calculations have been performed. Through these multi-scale calculations, the physical meanings of fluctuation field and activation volume which have been used phenomenologically become very clear. Experimental approaches for both microscopic and macroscopic thermally activated magnetization reversal processes and magnetic domain growths have been also performed. It is expected that these theoretical and experimental multi-scale studies will be integrated to fully understand the magnetic hysteresis and coercivity mechanism with the aid of data science technologies in the future.

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Section: はじめにunclassified

Recent Unrevealing on Magnetic Hysteresis of Permanent Magnets

Okamoto

2023

J. Japan Inst. Metals and Materials

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“…Grain boundary diffusion using non-magnetic elements is expected to improve magnetic properties, and many achievements have been made to improve these properties 14)~17) . For example, Bolyachkin et al reported that the coercivity was increased by infiltration of a Si cap layer into the grain boundary phase of Sm(Fe0.8Co0.2)12B0.5 (100 nm) thin film 16) . Then, microstructural observation by cross-sectional STEM-EDS revealed that the penetration depth of the diffused Si was found in a region approximately 25 nm from the top surface of the Sm(Fe0.8Co0.2)12B0.5 layer 16) .…”

Section: Introductionmentioning

confidence: 99%

“…For example, Bolyachkin et al reported that the coercivity was increased by infiltration of a Si cap layer into the grain boundary phase of Sm(Fe0.8Co0.2)12B0.5 (100 nm) thin film 16) . Then, microstructural observation by cross-sectional STEM-EDS revealed that the penetration depth of the diffused Si was found in a region approximately 25 nm from the top surface of the Sm(Fe0.8Co0.2)12B0.5 layer 16) . In addition, micromagnetic simulation based on the results of microstructural observation and magnetic properties predicts that a coercivity of 1.9 T will be obtained when diffused Si reaches 90 nm below the top surface of the Sm(Fe0.8Co0.2)12B0.5 layer; furthermore, if the formation of soft magnetic phases such as α-Fe or α-(Fe-Co) existing in the initial interface between the V buffer layer and the Sm(Fe0.8Co0.2)12B0.5 layer are suppressed completely, the coercivity will be enhanced to approximately 6.0 T 16) .…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Coercivity for Sm(Fe-Co)<sub>12</sub>-B Thin Films by Introduction of Sm Seed Layer

Mori,

Nakatsuka,

Hatanaka

et al. 2024

J. Magn. Soc. Jpn.

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To improve the coercivity of Sm(Fe-Co)12-B thin film, a Sm seed layer was introduced between a V buffer layer and a Sm(Fe-Co)12-B layer, and the thickness of the Sm(Fe-Co)12-B layer was varied. From the result of XRD patterns measured in an out-of-plane configuration, peaks from ( 002) and ( 004) of the ThMn12-type crystal structure were observed for all samples. The intensity of these peaks was reduced by decreasing the thickness of the Sm(Fe-Co)12-B layer; however, it was recovered by introducing a Sm seed layer. Although the coercivity was decreased due to the reduction in the thickness of the Sm(Fe-Co)12-B layer, a large coercivity of 1.87 T was obtained in an Al-diffused thin film, which was thinned to 50 nm while introducing a Sm seed layer.

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“…[1][2][3][4] ThMn 12 -type SmFe 12 -based permanent magnets have been recognized as the promising one of potential candidates because of their intrinsically high temperature stability of magnetic properties. [5][6][7][8][9][10][11] However, because of the metastable enhanced pinning effect of domain walls of magnetic hardening shells. [24,25] For the ThMn 12 -type alloys, Tozman et al recently proposed the first core-shell structure composed of Gd-rich shell and Gd-lean core in the (Sm,Gd)Fe 12 -based alloys.…”

Section: Introductionmentioning

confidence: 99%

“…[ 1–4 ] ThMn 12 ‐type SmFe 12 ‐based permanent magnets have been recognized as the promising one of potential candidates because of their intrinsically high temperature stability of magnetic properties. [ 5–11 ] However, because of the metastable characteristics, it still remains a challenge to achieve the single phase structure of SmFe 12 system in bulk magnets. [ 11,12 ]…”

Section: Introductionmentioning

confidence: 99%

Intrinsically High Magnetic Performance in Core–Shell Structural (Sm,Y)Fe₁₂‐Based Permanent Magnets

Zhao

Lin

et al. 2022

Advanced Materials

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ThMn12‐type SmFe12‐based permanent magnets have exhibited great potential in advanced magnet motors because of their high temperature stability of magnetic properties. However, the applications could be seriously limited due to the trade‐off between phase stability and intrinsic magnetic properties. In this work, an effective solution is demonstrated by constructing the core–shell structure (Sm‐rich shell and Y‐rich core) via a spontaneous spinodal decomposition process. The anisotropy field for the (Sm0.75Y0.25)(Fe0.8Co0.2)11.25Ti0.75 alloy is mostly optimized to be 9.24 T at room temperature. Such an enhancement is ascribed to the pinning process of domain walls by the magnetic‐hardening Sm‐rich shell, which is directly observed by in situ Lorentz transmission electron microscopy and reconstructed by micromagnetic simulation. Moreover, the phase stability and saturation magnetization are simultaneously increased, which is attributed to the synergistic effect of Y, Co, and Ti substitutions. More importantly, the high μ0Ms value of 1.52 T is comparable to the reported (Sm,Zr)Fe12‐based bulk alloys that contain a larger amount of soft α‐Fe phases, indicating that this strategy is more promising toward bulk magnets. The present study provides a significant concept for the development of advanced permanent magnets and also has implications for understanding the structural origin of intrinsic magnetic configurations.

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Coercivity engineering in Sm(Fe0.8Co0.2)12B0.5 thin films by Si grain boundary diffusion

Cited by 18 publications

References 26 publications

Recent Unrevealing on Magnetic Hysteresis of Permanent Magnets

Recent Unrevealing on Magnetic Hysteresis of Permanent Magnets

Enhancement of Coercivity for Sm(Fe-Co)<sub>12</sub>-B Thin Films by Introduction of Sm Seed Layer

Intrinsically High Magnetic Performance in Core–Shell Structural (Sm,Y)Fe₁₂‐Based Permanent Magnets

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Coercivity engineering in Sm(Fe0.8Co0.2)12B0.5 thin films by Si grain boundary diffusion

Cited by 18 publications

References 26 publications

Recent Unrevealing on Magnetic Hysteresis of Permanent Magnets

Recent Unrevealing on Magnetic Hysteresis of Permanent Magnets

Enhancement of Coercivity for Sm(Fe-Co)<sub>12</sub>-B Thin Films by Introduction of Sm Seed Layer

Intrinsically High Magnetic Performance in Core–Shell Structural (Sm,Y)Fe12‐Based Permanent Magnets

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Product

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Intrinsically High Magnetic Performance in Core–Shell Structural (Sm,Y)Fe₁₂‐Based Permanent Magnets