Anisotropic exchange in Nd–Fe–B permanent magnets

Qihua Gong; Min Yi; Richard F.L. Evans; Oliver Gutfleisch; Bai Xiang Xu

doi:10.1080/21663831.2019.1702116

Anisotropic exchange in Nd–Fe–B permanent magnets

Qihua Gong, Min Yi^*, Richard F.L. Evans, Oliver Gutfleisch, Bai Xiang Xu

^*Corresponding author for this work

Physics

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

Abstract

The exchange is critical for designing high-performance Nd–Fe–B permanent magnets. Here we demonstrate through multiscale simulations that the exchange in Nd–Fe–B magnets, including bulk exchange stiffness (A_e) in Nd₂Fe₁₄B phase and interface exchange coupling strength (J_int>) between Nd₂Fe₁₄B and grain boundary (GB), is strongly anisotropic. A_e is larger along crystallographic a/b axis than along c axis. Even when the GB Fe_xNd_1–x has the same composition, J_int for (100) interface is much higher than that for (001) interface. The discovered anisotropic exchange is shown to have profound influence on the coercivity. These findings enable more freedom in designing Nd–Fe–B magnets by tuning exchange. IMPACT STATEMENT: Bulk exchange stiffness in Nd₂Fe₁₄B and interface exchange coupling strength between Nd₂Fe₁₄B and grain boundary are found strongly anisotropic, which have profound influence on the coercivity of Nd–Fe–B magnets.

Original language	English
Pages (from-to)	89-96
Number of pages	8
Journal	Materials Research Letters
Volume	8
Issue number	3
Early online date	18 Dec 2019
DOIs	https://doi.org/10.1080/21663831.2019.1702116
Publication status	E-pub ahead of print - 18 Dec 2019

Bibliographical note

Keywords

coercivity
grain boundary
interface exchange
multiscale simulations
Permanent magnets

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10.1080/21663831.2019.1702116

2019MaterResLett-AnisotropicExchange
© 2019 The Author(s)
Final published version, 1.95 MBLicence: CC BY

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title = "Anisotropic exchange in Nd–Fe–B permanent magnets",

abstract = "The exchange is critical for designing high-performance Nd–Fe–B permanent magnets. Here we demonstrate through multiscale simulations that the exchange in Nd–Fe–B magnets, including bulk exchange stiffness (Ae) in Nd2Fe14B phase and interface exchange coupling strength (Jint>) between Nd2Fe14B and grain boundary (GB), is strongly anisotropic. Ae is larger along crystallographic a/b axis than along c axis. Even when the GB FexNd1–x has the same composition, Jint for (100) interface is much higher than that for (001) interface. The discovered anisotropic exchange is shown to have profound influence on the coercivity. These findings enable more freedom in designing Nd–Fe–B magnets by tuning exchange. IMPACT STATEMENT: Bulk exchange stiffness in Nd2Fe14B and interface exchange coupling strength between Nd2Fe14B and grain boundary are found strongly anisotropic, which have profound influence on the coercivity of Nd–Fe–B magnets.",

keywords = "coercivity, grain boundary, interface exchange, multiscale simulations, Permanent magnets",

author = "Qihua Gong and Min Yi and Evans, {Richard F.L.} and Oliver Gutfleisch and Xu, {Bai Xiang}",

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T1 - Anisotropic exchange in Nd–Fe–B permanent magnets

AU - Gong, Qihua

AU - Yi, Min

AU - Evans, Richard F.L.

AU - Gutfleisch, Oliver

AU - Xu, Bai Xiang

PY - 2019/12/18

Y1 - 2019/12/18

N2 - The exchange is critical for designing high-performance Nd–Fe–B permanent magnets. Here we demonstrate through multiscale simulations that the exchange in Nd–Fe–B magnets, including bulk exchange stiffness (Ae) in Nd2Fe14B phase and interface exchange coupling strength (Jint>) between Nd2Fe14B and grain boundary (GB), is strongly anisotropic. Ae is larger along crystallographic a/b axis than along c axis. Even when the GB FexNd1–x has the same composition, Jint for (100) interface is much higher than that for (001) interface. The discovered anisotropic exchange is shown to have profound influence on the coercivity. These findings enable more freedom in designing Nd–Fe–B magnets by tuning exchange. IMPACT STATEMENT: Bulk exchange stiffness in Nd2Fe14B and interface exchange coupling strength between Nd2Fe14B and grain boundary are found strongly anisotropic, which have profound influence on the coercivity of Nd–Fe–B magnets.

AB - The exchange is critical for designing high-performance Nd–Fe–B permanent magnets. Here we demonstrate through multiscale simulations that the exchange in Nd–Fe–B magnets, including bulk exchange stiffness (Ae) in Nd2Fe14B phase and interface exchange coupling strength (Jint>) between Nd2Fe14B and grain boundary (GB), is strongly anisotropic. Ae is larger along crystallographic a/b axis than along c axis. Even when the GB FexNd1–x has the same composition, Jint for (100) interface is much higher than that for (001) interface. The discovered anisotropic exchange is shown to have profound influence on the coercivity. These findings enable more freedom in designing Nd–Fe–B magnets by tuning exchange. IMPACT STATEMENT: Bulk exchange stiffness in Nd2Fe14B and interface exchange coupling strength between Nd2Fe14B and grain boundary are found strongly anisotropic, which have profound influence on the coercivity of Nd–Fe–B magnets.

KW - coercivity

KW - grain boundary

KW - interface exchange

KW - multiscale simulations

KW - Permanent magnets

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DO - 10.1080/21663831.2019.1702116

M3 - Article

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SN - 2166-3831

VL - 8

SP - 89

EP - 96

JO - Materials Research Letters

JF - Materials Research Letters

IS - 3

ER -

Anisotropic exchange in Nd–Fe–B permanent magnets

Abstract

Bibliographical note

Keywords

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