Relevance of 4f-3d exchange to finite-temperature magnetism of rare-earth permanent magnets: An ab-initio-based spin model approach for NdFe12N

Matsumoto, Munehisa; Akai, H.; Harashima, Yosuke; Doi, Shotaro; Miyake, Takashi

doi:10.1063/1.4952989

Cited by 24 publications

(18 citation statements)

References 22 publications

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“…We focus on the Ce-Fe "1-12" material system 4,7,17,20,21 , which has recently been under scrutiny as a potential hard magnet 16,22,23 . Our calculations show a significant reduction of the Ce magnetic moment due to the Kondo effect.…”

Section: Introductionmentioning

confidence: 99%

Intrinsically weak magnetic anisotropy of cerium in potential hard-magnetic intermetallics

et al. 2021

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Cerium-based intermetallics are currently attracting much interest as a possible alternative to existing high-performance magnets containing scarce heavy rare-earth elements. However, the intrinsic magnetic properties of Ce in these systems are poorly understood due to the difficulty of a quantitative description of the Kondo effect, a many-body phenomenon where conduction electrons screen out the Ce-4f moment. Here, we show that the Ce-4f shell in Ce–Fe intermetallics is partially Kondo screened. The Kondo scale is dramatically enhanced by nitrogen interstitials suppressing the Ce-4f contribution to the magnetic anisotropy, in striking contrast to the effect of nitrogenation in isostructural intermetallics containing other rare-earth elements. We determine the full temperature dependence of the Ce-4f single-ion anisotropy and show that even unscreened Ce-4f moments contribute little to the room-temperature intrinsic magnetic hardness. Our study thus establishes fundamental constraints on the potential of cerium-based permanent magnet intermetallics.

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Section: Introductionmentioning

confidence: 99%

Intrinsically weak magnetic anisotropy of cerium in potential hard-magnetic intermetallics

et al. 2021

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“…9,10 However, there remains a gap between our microscopic picture and the macroscopic aspects of MA since previous theoretical studies on the temperature dependence of MA for R 2 Fe 14 B magnets are based on complete diagonalization of the Hamiltonian 9,10 or numerical methods such as the Monte Carlo method. 4,11,12 An effective means of bridging this gap is to develop a power-law theory 5,6,[13][14][15][16][17][18] to establish the relationship between MACs and magnetization. The history of investigations on MA based on the power-law theory has been reviewed by Callen and Callen.…”

Section: Introductionmentioning

confidence: 99%

Power law analysis for temperature dependence of magnetocrystalline anisotropy constants of Nd2Fe14B magnets

Miura

Sakuma

2018

AIP Advances

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We perform phenomenological analysis of the temperature dependence of magnetocrystalline anisotropy (MA) in rare-earth magnets. We define the phenomenological power laws applicable to compound magnets using the Zener theory, and we apply these laws to study the magnetocrystalline anisotropy constants (MACs) of Nd2Fe14B magnets. The results indicate that the MACs closely obey the power law, and further, our analysis yields a better understanding of the temperaturedependent MA in rare-earth magnets. Furthermore, to examine the validity of the power law, we discuss the temperature dependence of the MACs in Dy2Fe14B and Y2Fe14B magnets as examples of cases wherein it is difficult to interpret the MA using the power law.

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“…Since the Nd-5d spin is anti-parallel to the total moment, its magnetic moment is reduced as the level of the hybridized state is downshifted. The change in the Nd-5d moment is correlated with the exchange coupling between Nd and surrounding Fe sites [ 79 ], which is a key quantity for the temperature dependence of the anisotropy field [ 80 ].…”

Section: Magnetism and Stability Of Nd 2 Fe 14 B And R Fe 12mentioning

confidence: 99%

Understanding and optimization of hard magnetic compounds from first principles

Miyake

Harashima

Fukazawa

et al. 2021

Science and Technology of Advanced Materials

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First-principles calculation based on density functional theory is a powerful tool for understanding and designing magnetic materials. It enables us to quantitatively describe magnetic properties and structural stability, although further methodological developments for the treatment of strongly-correlated 4f electrons and finite-temperature magnetism are needed. Here, we review recent developments of computational schemes for rare-earth magnet compounds, and summarize our theoretical studies on Nd 2 Fe 14 B and R Fe 12 -type compounds. Effects of chemical substitution and interstitial dopants are clarified. We also discuss how data-driven approaches are used for studying multinary systems. Chemical composition can be optimized with fewer trials by the Bayesian optimization. We also present a data-assimilation method for predicting finitetemperature magnetization in wide composition space by integrating computational and experimental data.

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Relevance of 4f-3d exchange to finite-temperature magnetism of rare-earth permanent magnets: An ab-initio-based spin model approach for NdFe12N

Cited by 24 publications

References 22 publications

Intrinsically weak magnetic anisotropy of cerium in potential hard-magnetic intermetallics

Intrinsically weak magnetic anisotropy of cerium in potential hard-magnetic intermetallics

Power law analysis for temperature dependence of magnetocrystalline anisotropy constants of Nd2Fe14B magnets

Understanding and optimization of hard magnetic compounds from first principles

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