Dipolar energy of Nd-Fe-B nanocrystalline magnets in magnetization reversal process

Ohtori, Hiroyuki; Iwano, Kaoru; Mitsumata, Chiharu; Yano, Masao; Kato, Akira; Shoji, Tetsuya; Manabe, Akira; Ono, Kanta

doi:10.1063/1.4864041

Cited by 6 publications

(5 citation statements)

References 28 publications

(24 reference statements)

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“…This characteristic is also demonstrated by using scanning transmission x-ray microscopy for Nd-Fe-B nanocrystalline magnets. [24] In addition, the flatness of the M r (H) and DM curves (see Fig. 4(a), DM from Fig.…”

Section: Resultsmentioning

confidence: 87%

Enhanced coercivity and remanence of PrCo ₅ nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

Zuo¹,

Zhao²,

Xiong³

et al. 2015

Chinese Phys. B

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PrCo5 nanoflakes with strong texture and high coercivity of 8.15 kOe were prepared by surfactant-assisted ball milling with heat-treated starting powder. The thickness and length of the as-milled nanoflakes are mainly in the ranges of 50–100 nm and 0.5–3 μm, respectively. The x-ray diffraction patterns demonstrate that the heat treatment can increase the single phase and crystallinity of the PrCo5 compound, and combined with the demagnetization curves, indicate that the single phase and crystallinity are important for preparing high-coercivity and strong-textured rare earth permanent magnetic nanoflakes. In addition, the coercivity mechanism of the as-milled PrCo5 nanoflakes is studied by the angle dependence of coercivity for an aligned sample and the field dependence of coercivity, isothermal (IRM) and dc demagnetizing (DCD) remanence curves for an unaligned sample. The results indicate that the coercivity is dominated by co-existing mechanisms of pinning and nucleation. Furthermore, exchange coupling and dipolar coupling also co-exist in the sample.

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Section: Resultsmentioning

confidence: 87%

Enhanced coercivity and remanence of PrCo ₅ nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

Zuo¹,

Zhao²,

Xiong³

et al. 2015

Chinese Phys. B

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“…3e, and these fields are positive or almost zero inside the grains. In contrast, the dipole field has a nonuniform distribution 57,58 and a negative value in region A; the strength of the dipole field reaches 1.76 T in the z-direction. The total magnetic field approaches 4.56 T around region A, which exceeds the switching field of this grain.…”

Section: Demagnetization Curve and Magnetization Reversalmentioning

confidence: 95%

Relationship between magnetic nucleation and the microstructure of a hot-deformed permanent magnet: micromagnetic simulation

et al. 2020

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The grains initiating magnetization reversal in the microstructure of a hot-deformed permanent magnet have been identified in this study by performing micromagnetic simulations based on the Landau-Lifshitz-Gilbert equation. Hotdeformed permanent magnets comprise tabular grains, the easy-axis orientations of which are inclined with respect to the nominal easy axis of the permanent magnet. In the simulation model, the grains complexly overlap, similar to in actual permanent magnets. We analyze the simulation results considering grain overlap and the easy-axis tilt angles of the grains. The initiation of magnetic nucleation requires a high concentration of grains with large easy-axis tilt angles. We clarify the magnetic-nucleation process and provide a method to enhance the performance of permanent magnets by avoiding a high concentration of grains with large easy-axis tilt angles.

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“…Finally, the influence of the non-magnetic phase was investigated by comparing these results with those for a Nd-Fe-B nanocrystalline magnet without Nd-Cu layers. 31…”

Section: Image Analysismentioning

confidence: 99%

“…In a previous study, 31 we analyzed a STXM image of an Nd-Fe-B nanocrystalline magnet without Nd-Cu layers and obtained a 2D distribution of the magnetic dipolar interaction energies using Eq. (6).…”

Section: Visualizationmentioning

confidence: 99%

Dipolar energies in Nd-Fe-B nanocrystalline magnets with and without Nd-Cu infiltration

Ohtori

Iwano

Mitsumata

et al. 2015

Journal of Applied Physics

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We analyze the dipolar energies of Nd-Cu-infiltrated Nd-Fe-B nanocrystalline magnets during magnetization reversals by visualizing the magnetic dipolar interactions. Non-magnetic phases from the grains were identified by analyzing the element-specific magnetization distribution images taken with scanning transmission X-ray microscopy. The magnetic dipolar interactions were calculated from the interactions between the magnetization at each point and those at other points in the scanning transmission X-ray microscopy images. We present the dipolar energy distributions in Nd-Cu infiltrated nanocrystalline Nd-Fe-B magnets and compare them with those in nanocrystalline Nd-Fe-B magnets without Nd-Cu infiltration. The interplay between the exchange and dipolar interactions in Nd-Fe-B magnets is found to be essential for obtaining high coercivities. V

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Dipolar energy of Nd-Fe-B nanocrystalline magnets in magnetization reversal process

Cited by 6 publications

References 28 publications

Enhanced coercivity and remanence of PrCo ₅ nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

Enhanced coercivity and remanence of PrCo ₅ nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

Relationship between magnetic nucleation and the microstructure of a hot-deformed permanent magnet: micromagnetic simulation

Dipolar energies in Nd-Fe-B nanocrystalline magnets with and without Nd-Cu infiltration

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Dipolar energy of Nd-Fe-B nanocrystalline magnets in magnetization reversal process

Cited by 6 publications

References 28 publications

Enhanced coercivity and remanence of PrCo 5 nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

Enhanced coercivity and remanence of PrCo 5 nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

Relationship between magnetic nucleation and the microstructure of a hot-deformed permanent magnet: micromagnetic simulation

Dipolar energies in Nd-Fe-B nanocrystalline magnets with and without Nd-Cu infiltration

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Product

Resources

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Enhanced coercivity and remanence of PrCo ₅ nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

Enhanced coercivity and remanence of PrCo ₅ nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder