First-order reversal curve analysis of a Nd-Fe-B sintered magnet with soft X-ray magnetic circular dichroism microscopy

Kazunori Miyazawa; Satoshi Okamoto; Takahiro Yomogita; Nobuaki Kikuchi; Osamu Kitakami; Kentaro Toyoki; David Billington; Yoshinori Kotani; Tetsuya Nakamura; Taisuke Sasaki; Tadakatsu Ohkubo; Kazuhiro Hono

doi:10.1016/j.actamat.2018.09.053

First-order reversal curve analysis of a Nd-Fe-B sintered magnet with soft X-ray magnetic circular dichroism microscopy

Kazunori Miyazawa, Satoshi Okamoto, Takahiro Yomogita, Nobuaki Kikuchi, Osamu Kitakami, Kentaro Toyoki, David Billington, Yoshinori Kotani, Tetsuya Nakamura, Taisuke Sasaki, Tadakatsu Ohkubo, Kazuhiro Hono

Research output: Contribution to journal › Article › peer-review

20 Citations (Scopus)

Abstract

First-order reversal curve (FORC) diagram, which visualizes the variation of magnetic susceptibility on a field plane, has been applied to a Nd-Fe-B sintered magnet. The FORC diagram exhibits the characteristic behavior of two remarkable spots in low-field and high-field regions. The high-field FORC spot corresponds to the irreversible magnetization reversal at a coercive field, whereas the low-field FORC spot indicates the appearance of a large magnetic susceptibility state during the demagnetization process. Moreover, this low-field FORC spot becomes dominant at high temperature, accompanied by a significant reduction in coercivity. These results suggest that the low-field FORC spot has a strong correlation with the degradation of magnetic properties of a Nd-Fe-B sintered magnet. To clarify the actual magnetization reversal processes corresponding to these two FORC spots, soft X-ray magnetic circular dichroism (XMCD) microscopy observation was employed with similar field sequences of the FORC measurements. Consequently, the low-field FORC spot is mainly attributed to the domain wall motion in multi-domain grains, whereas the high-field FORC spot corresponds to the magnetization reversal of single-domain grains. These indicate that a FORC diagram is a powerful evaluation method for the magnetization reversal processes of permanent magnets.

Original language	English
Pages (from-to)	1-9
Number of pages	9
Journal	Acta Materialia
Volume	162
DOIs	https://doi.org/10.1016/j.actamat.2018.09.053
Publication status	Published - 2019 Jan 1

Keywords

FORC
Magnetization reversal
Nd-Fe-B magnet
XMCD

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Ceramics and Composites
Polymers and Plastics
Metals and Alloys

Access to Document

10.1016/j.actamat.2018.09.053

Cite this

@article{9836f6e02ee942419c27287671d8528b,

title = "First-order reversal curve analysis of a Nd-Fe-B sintered magnet with soft X-ray magnetic circular dichroism microscopy",

abstract = "First-order reversal curve (FORC) diagram, which visualizes the variation of magnetic susceptibility on a field plane, has been applied to a Nd-Fe-B sintered magnet. The FORC diagram exhibits the characteristic behavior of two remarkable spots in low-field and high-field regions. The high-field FORC spot corresponds to the irreversible magnetization reversal at a coercive field, whereas the low-field FORC spot indicates the appearance of a large magnetic susceptibility state during the demagnetization process. Moreover, this low-field FORC spot becomes dominant at high temperature, accompanied by a significant reduction in coercivity. These results suggest that the low-field FORC spot has a strong correlation with the degradation of magnetic properties of a Nd-Fe-B sintered magnet. To clarify the actual magnetization reversal processes corresponding to these two FORC spots, soft X-ray magnetic circular dichroism (XMCD) microscopy observation was employed with similar field sequences of the FORC measurements. Consequently, the low-field FORC spot is mainly attributed to the domain wall motion in multi-domain grains, whereas the high-field FORC spot corresponds to the magnetization reversal of single-domain grains. These indicate that a FORC diagram is a powerful evaluation method for the magnetization reversal processes of permanent magnets.",

keywords = "FORC, Magnetization reversal, Nd-Fe-B magnet, XMCD",

author = "Kazunori Miyazawa and Satoshi Okamoto and Takahiro Yomogita and Nobuaki Kikuchi and Osamu Kitakami and Kentaro Toyoki and David Billington and Yoshinori Kotani and Tetsuya Nakamura and Taisuke Sasaki and Tadakatsu Ohkubo and Kazuhiro Hono",

note = "Funding Information: We gratefully thank Dr. S. Hirosawa for valuable advice and fruitful discussion. This work was partially supported by Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials from MEXT , the Management Expenses Grants for National Universities Corporations from MEXT , JSPS KAKENHI Grant No. 17H03376 , JST , Collaborative Research Based on Industrial Demand , and NIMS Joint Research Hub Program. The XMCD microscopy experiments have been performed at SPring-8 with the approval of JASRI (Proposal Nos. 2015A2042 , 2015B1998 , 2017A1022 , and 2017B1028 ). Funding Information: We gratefully thank Dr. S. Hirosawa for valuable advice and fruitful discussion. This work was partially supported by Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials from MEXT, the Management Expenses Grants for National Universities Corporations from MEXT, JSPS KAKENHI Grant No. 17H03376, JST, Collaborative Research Based on Industrial Demand, and NIMS Joint Research Hub Program. The XMCD microscopy experiments have been performed at SPring-8 with the approval of JASRI (Proposal Nos. 2015A2042, 2015B1998, 2017A1022, and 2017B1028). Publisher Copyright: {\textcopyright} 2018 Acta Materialia Inc.",

year = "2019",

month = jan,

day = "1",

doi = "10.1016/j.actamat.2018.09.053",

language = "English",

volume = "162",

pages = "1--9",

journal = "Acta Materialia",

issn = "1359-6454",

publisher = "Elsevier Limited",

}

TY - JOUR

T1 - First-order reversal curve analysis of a Nd-Fe-B sintered magnet with soft X-ray magnetic circular dichroism microscopy

AU - Miyazawa, Kazunori

AU - Okamoto, Satoshi

AU - Yomogita, Takahiro

AU - Kikuchi, Nobuaki

AU - Kitakami, Osamu

AU - Toyoki, Kentaro

AU - Billington, David

AU - Kotani, Yoshinori

AU - Nakamura, Tetsuya

AU - Sasaki, Taisuke

AU - Ohkubo, Tadakatsu

AU - Hono, Kazuhiro

N1 - Funding Information: We gratefully thank Dr. S. Hirosawa for valuable advice and fruitful discussion. This work was partially supported by Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials from MEXT , the Management Expenses Grants for National Universities Corporations from MEXT , JSPS KAKENHI Grant No. 17H03376 , JST , Collaborative Research Based on Industrial Demand , and NIMS Joint Research Hub Program. The XMCD microscopy experiments have been performed at SPring-8 with the approval of JASRI (Proposal Nos. 2015A2042 , 2015B1998 , 2017A1022 , and 2017B1028 ). Funding Information: We gratefully thank Dr. S. Hirosawa for valuable advice and fruitful discussion. This work was partially supported by Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials from MEXT, the Management Expenses Grants for National Universities Corporations from MEXT, JSPS KAKENHI Grant No. 17H03376, JST, Collaborative Research Based on Industrial Demand, and NIMS Joint Research Hub Program. The XMCD microscopy experiments have been performed at SPring-8 with the approval of JASRI (Proposal Nos. 2015A2042, 2015B1998, 2017A1022, and 2017B1028). Publisher Copyright: © 2018 Acta Materialia Inc.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - First-order reversal curve (FORC) diagram, which visualizes the variation of magnetic susceptibility on a field plane, has been applied to a Nd-Fe-B sintered magnet. The FORC diagram exhibits the characteristic behavior of two remarkable spots in low-field and high-field regions. The high-field FORC spot corresponds to the irreversible magnetization reversal at a coercive field, whereas the low-field FORC spot indicates the appearance of a large magnetic susceptibility state during the demagnetization process. Moreover, this low-field FORC spot becomes dominant at high temperature, accompanied by a significant reduction in coercivity. These results suggest that the low-field FORC spot has a strong correlation with the degradation of magnetic properties of a Nd-Fe-B sintered magnet. To clarify the actual magnetization reversal processes corresponding to these two FORC spots, soft X-ray magnetic circular dichroism (XMCD) microscopy observation was employed with similar field sequences of the FORC measurements. Consequently, the low-field FORC spot is mainly attributed to the domain wall motion in multi-domain grains, whereas the high-field FORC spot corresponds to the magnetization reversal of single-domain grains. These indicate that a FORC diagram is a powerful evaluation method for the magnetization reversal processes of permanent magnets.

AB - First-order reversal curve (FORC) diagram, which visualizes the variation of magnetic susceptibility on a field plane, has been applied to a Nd-Fe-B sintered magnet. The FORC diagram exhibits the characteristic behavior of two remarkable spots in low-field and high-field regions. The high-field FORC spot corresponds to the irreversible magnetization reversal at a coercive field, whereas the low-field FORC spot indicates the appearance of a large magnetic susceptibility state during the demagnetization process. Moreover, this low-field FORC spot becomes dominant at high temperature, accompanied by a significant reduction in coercivity. These results suggest that the low-field FORC spot has a strong correlation with the degradation of magnetic properties of a Nd-Fe-B sintered magnet. To clarify the actual magnetization reversal processes corresponding to these two FORC spots, soft X-ray magnetic circular dichroism (XMCD) microscopy observation was employed with similar field sequences of the FORC measurements. Consequently, the low-field FORC spot is mainly attributed to the domain wall motion in multi-domain grains, whereas the high-field FORC spot corresponds to the magnetization reversal of single-domain grains. These indicate that a FORC diagram is a powerful evaluation method for the magnetization reversal processes of permanent magnets.

KW - FORC

KW - Magnetization reversal

KW - Nd-Fe-B magnet

KW - XMCD

UR - http://www.scopus.com/inward/record.url?scp=85054159690&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85054159690&partnerID=8YFLogxK

U2 - 10.1016/j.actamat.2018.09.053

DO - 10.1016/j.actamat.2018.09.053

M3 - Article

AN - SCOPUS:85054159690

SN - 1359-6454

VL - 162

SP - 1

EP - 9

JO - Acta Materialia

JF - Acta Materialia

ER -

First-order reversal curve analysis of a Nd-Fe-B sintered magnet with soft X-ray magnetic circular dichroism microscopy

Abstract

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this