First-principles Study of Spin-Wave Dispersion in Sm(FeCo)<sub>12</sub>

Fukazawa, Taro; Akai, H.; Harashima, Yosuke; Miyake, Takashi

doi:10.1109/intmag.2018.8508731

Cited by 3 publications

(4 citation statements)

References 18 publications

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“…The material parameters are taken from our DFT values and ref. [43]. The saturation magnetization (μ 0 M s ), the magnetocrystalline anisotropy constant ( K 1 ), and the exchange stiffness ( A ) were 1.48 T, 4.76 MJ m −3 and 9.5 PJ m −1 for Sm 0.75 Y 0.25 (Fe 0.8 Co 0.2 ) 11.25 Ti 0.75 , 1.47 T, 5.11 MJ m −3 and 9.6 PJ m −1 for Sm 0.8 Y 0.2 (Fe 0.8 Co 0.2 ) 11.25 Ti 0.75 , 1.49 T, 4.48 MJ m −3 and 9.4 PJ m −1 for Sm 0.7 Y 0.3 (Fe 0.8 Co 0.2 ) 11.25 Ti 0.75 , respectively.…”

Section: Methodsmentioning

confidence: 99%

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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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Section: Methodsmentioning

confidence: 99%

“…The mesh size was 2 × 2 × 2 nm3 . The material parameters are taken from our DFT values and ref [43]…”

mentioning

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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“…To handle this issue, Hasegawa and Yanase pioneered a simple approach by treating the f electrons as core electrons, namely the 4f-in-core approximation. [27][28][29][30][31] For the purpose of alleviating the computational load and avoiding the problematic nature of the 4f shell electrons in monolayer NdN 2 , the 4f-in-core approximation was adopted in this study. The pseudopotential for the Nd atom containing 11 electrons was used, and the 5s 2 5p 6 5d 1 6s 2 valence-electron configuration was considered.…”

Section: Computational Detailsmentioning

confidence: 99%

Quantum anomalous Hall effect with a high and tunable Chern number in monolayer NdN₂

et al. 2023

Phys. Chem. Chem. Phys.

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“…The method used in our approaches is general and can be applied for other systems. For example, similar calculations have also been carried out for the magnets SmCo 5 [77] and SmFe 12 [78]. ( ) ( )…”

Section: Anisotropy Of Exchange Stiffness Constantmentioning

confidence: 99%

Atomistic theory of thermally activated magnetization processes in Nd₂Fe₁₄B permanent magnet

Miyashita

Nishino

Toga

et al. 2021

Science and Technology of Advanced Materials

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For the practical use of magnets, particularly at high temperatures, the temperature dependence of magnetic properties is an important ingredient. To study the temperature dependence, methods of treating the thermal fluctuation causing the so-called activation phenomena must be established. To study finite-temperature properties quantitatively, we need atomistic energy information to calculate the canonical distribution. In the present review, we report our recent studies on the thermal properties of the Nd 2 Fe 14 B magnet and the methods of studying them. We first propose an atomistic Hamiltonian and show various thermodynamic properties, e.g., the temperature dependences of the magnetization showing a spin reorientation transition, the magnetic anisotropy energy, the domain wall profiles, the anisotropy of the exchange stiffness constant, and the spectrum of ferromagnetic resonance. The effects of the dipole-dipole interaction (DDI) in large grains are also presented. In addition to these equilibrium properties, we also study coercivity, which is the most important issue for magnets. The temperature dependence of the coercivity of a single grain was studied using the stochastic Landau-Lifshitz-Gilbert equation and also by the analysis of the free energy landscape, which was obtained by Monte Carlo simulation. It was found that the upper limit of coercivity at room temperature is about 3T, which is significantly lower than the so-called theoretical coercivity given by a simple coherent rotation model. The coercivity of a polycrystalline magnet, i.e., an ensemble of grains, is expected to be reduced further by the effects of the grain boundary phase, which is also studied. Surface nucleation is a key ingredient in the domain wall depinning process. Finally, we study the effect of DDI among grains and also discuss the distribution of properties of grains from the viewpoint of first order reversal curve.

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First-principles Study of Spin-Wave Dispersion in Sm(FeCo)₁₂

Cited by 3 publications

References 18 publications

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

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

Quantum anomalous Hall effect with a high and tunable Chern number in monolayer NdN₂

Atomistic theory of thermally activated magnetization processes in Nd₂Fe₁₄B permanent magnet

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First-principles Study of Spin-Wave Dispersion in Sm(FeCo)12

Cited by 3 publications

References 18 publications

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

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

Quantum anomalous Hall effect with a high and tunable Chern number in monolayer NdN2

Atomistic theory of thermally activated magnetization processes in Nd2Fe14B permanent magnet

Contact Info

Product

Resources

About

First-principles Study of Spin-Wave Dispersion in Sm(FeCo)₁₂

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

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

Quantum anomalous Hall effect with a high and tunable Chern number in monolayer NdN₂

Atomistic theory of thermally activated magnetization processes in Nd₂Fe₁₄B permanent magnet