Transmission electron microscopy image based micromagnetic simulations for optimizing nanostructure of FePt-X heat-assisted magnetic recording media

Bolyachkin, A.; Sepehri-Amin, H.; Suzuki, Itsuko S.; Tajiri, Hiroo; Takahashi, Y. K.; Srinivasan, Kumar; Ho, H. Y.; Yuan, Hua; Seki, T.; Ajan, Antony; Hono, K.

doi:10.1016/j.actamat.2022.117744

Cited by 16 publications

(2 citation statements)

References 40 publications

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“…解析などの巨視的な解析手法に加え [20][21][22] ，最近では磁気トモグラフィー測定による微視的な解析手法も整備されつつある [23][24][25] ．また，Micromagnetic (MM) シミュレーションも大きな進展を見せており [26][27][28][29][30][31] ，計算機や計算アルゴリズムの進化に加えて機械学習を導入した高速化，大規模化 [32][33][34] や電子顕微鏡で得た実際の微細組織構造をモデリングする手法の開発 [35][36][37] なども進められている． ÁEðM; HÞ ¼ EðM [20][21][22]62)…”

Section: はじめにunclassified

Recent Unrevealing on Magnetic Hysteresis of Permanent Magnets

Okamoto

2023

J. Japan Inst. Metals and Materials

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Magnetic hysteresis and coercivity mechanism of a permanent magnet have been long discussed, and their understandings have been significantly deepened during the last decade. Magnetization reversal in a permanent magnet proceeds with thermally activated nucleation and domain wall depinning processes followed by magnetic domain expansions. To treat theoretically the thermally activated magnetization reversal process, atomistic spin model and continuum calculations have been performed. Through these multi-scale calculations, the physical meanings of fluctuation field and activation volume which have been used phenomenologically become very clear. Experimental approaches for both microscopic and macroscopic thermally activated magnetization reversal processes and magnetic domain growths have been also performed. It is expected that these theoretical and experimental multi-scale studies will be integrated to fully understand the magnetic hysteresis and coercivity mechanism with the aid of data science technologies in the future.

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Section: はじめにunclassified

Recent Unrevealing on Magnetic Hysteresis of Permanent Magnets

Okamoto

2023

J. Japan Inst. Metals and Materials

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“…size. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] However, in the case of magnetic recording media, the high grain density will be essential to obtain high signal to noise ratio in high areal density. As mentioned in the introduction even if grain coalescence is suppressed, the required grain density of 24 T in −2 for 4 Tbit in −2 cannot be achieved in our sputtering process.…”

Section: Introductionmentioning

confidence: 99%

Grain density control in FePt granular films for heat-assisted magnetic recording media

Suzuki

Takahashi

2022

Jpn. J. Appl. Phys.

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To realize high areal density hard disk drives (HDDs) larger than 4 Tbit/in2, ultrafine FePt grains of less than 5 nm and grain density larger than 24 T/in2 are required. Although there have been many investigations to reduce the grain size of FePt, there are few reports on the control of grain density. To increase the grain density, we focused on three aspects of the surface morphology and grain density: nucleation sites on the substrate surface, surface free energy, and lattice mismatch. We achieved 14 T/in2 by maximizing the number of nucleation sites in the FePt-C granular film and found that the surface free energy and lattice mismatch are crucial parameters for controlling the grain density.

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