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

A. Bolyachkin; H. Sepehri-Amin; I. Suzuki; H. Tajiri; Y. K. Takahashi; K. Srinivasan; H. Ho; H. Yuan; T. Seki; A. Ajan; K. Hono

doi:10.1016/j.actamat.2022.117744

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

A. Bolyachkin, H. Sepehri-Amin^*, I. Suzuki, H. Tajiri, Y. K. Takahashi, K. Srinivasan, H. Ho, H. Yuan, T. Seki, A. Ajan, K. Hono

^*Corresponding author for this work

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

6 Citations (Scopus)

Abstract

The areal density of the heat-assisted magnetic recording (HAMR) technology has a potential to reach 4 Tb/in². However, the bimodal grain size distribution and structural defects that are unavoidable in actual FePt-X nanogranular media must be minimized for further reduction of a jitter noise. Here we report transmission electron microscopy (TEM) image based micromagnetic simulations of the FePt-X nanogranular media in order to elucidate the role of structural defects such as [200] misalignment and {111} twins on the magnetic properties. Micromagnetic approximation of experimental out-of-plane hysteresis loops allows to evaluate micromagnetic parameters and volume fractions of the defects in MgO(6 nm)/FePt-BN(1 nm)/FePt-(BN,C,SiO₂)(7 nm) granular thin films. Synchrotron XRD of the films validated that the structural defects can be accurately evaluated by the proposed approach. The developed TEM image based micromagnetic simulations can directly link nanostructure of the FePt-X media with magnetic properties, boosting not only the optimization of the HAMR media but also a design of magnetic nanomaterials in general.

Original language	English
Article number	117744
Journal	Acta Materialia
Volume	227
DOIs	https://doi.org/10.1016/j.actamat.2022.117744
Publication status	Published - 2022 Apr 1
Externally published	Yes

Keywords

FePt
Heat-assisted magnetic recording
Micromagnetic simulation
Nanostructure

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Ceramics and Composites
Polymers and Plastics
Metals and Alloys

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10.1016/j.actamat.2022.117744

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Bolyachkin, A., Sepehri-Amin, H., Suzuki, I., Tajiri, H., Takahashi, Y. K., Srinivasan, K., Ho, H., Yuan, H., Seki, T., Ajan, A., & Hono, K. (2022). Transmission electron microscopy image based micromagnetic simulations for optimizing nanostructure of FePt-X heat-assisted magnetic recording media. Acta Materialia, 227, [117744]. https://doi.org/10.1016/j.actamat.2022.117744

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

abstract = "The areal density of the heat-assisted magnetic recording (HAMR) technology has a potential to reach 4 Tb/in2. However, the bimodal grain size distribution and structural defects that are unavoidable in actual FePt-X nanogranular media must be minimized for further reduction of a jitter noise. Here we report transmission electron microscopy (TEM) image based micromagnetic simulations of the FePt-X nanogranular media in order to elucidate the role of structural defects such as [200] misalignment and {111} twins on the magnetic properties. Micromagnetic approximation of experimental out-of-plane hysteresis loops allows to evaluate micromagnetic parameters and volume fractions of the defects in MgO(6 nm)/FePt-BN(1 nm)/FePt-(BN,C,SiO2)(7 nm) granular thin films. Synchrotron XRD of the films validated that the structural defects can be accurately evaluated by the proposed approach. The developed TEM image based micromagnetic simulations can directly link nanostructure of the FePt-X media with magnetic properties, boosting not only the optimization of the HAMR media but also a design of magnetic nanomaterials in general.",

keywords = "FePt, Heat-assisted magnetic recording, Micromagnetic simulation, Nanostructure",

author = "A. Bolyachkin and H. Sepehri-Amin and I. Suzuki and H. Tajiri and Takahashi, {Y. K.} and K. Srinivasan and H. Ho and H. Yuan and T. Seki and A. Ajan and K. Hono",

note = "Funding Information: This work was in-part supported by JSPS KAKENHI Grant Numbers JP19K05257 and JP18H03787 . Publisher Copyright: {\textcopyright} 2022",

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doi = "10.1016/j.actamat.2022.117744",

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AU - Bolyachkin, A.

AU - Sepehri-Amin, H.

AU - Suzuki, I.

AU - Tajiri, H.

AU - Takahashi, Y. K.

AU - Srinivasan, K.

AU - Ho, H.

AU - Yuan, H.

AU - Seki, T.

AU - Ajan, A.

AU - Hono, K.

PY - 2022/4/1

Y1 - 2022/4/1

N2 - The areal density of the heat-assisted magnetic recording (HAMR) technology has a potential to reach 4 Tb/in2. However, the bimodal grain size distribution and structural defects that are unavoidable in actual FePt-X nanogranular media must be minimized for further reduction of a jitter noise. Here we report transmission electron microscopy (TEM) image based micromagnetic simulations of the FePt-X nanogranular media in order to elucidate the role of structural defects such as [200] misalignment and {111} twins on the magnetic properties. Micromagnetic approximation of experimental out-of-plane hysteresis loops allows to evaluate micromagnetic parameters and volume fractions of the defects in MgO(6 nm)/FePt-BN(1 nm)/FePt-(BN,C,SiO2)(7 nm) granular thin films. Synchrotron XRD of the films validated that the structural defects can be accurately evaluated by the proposed approach. The developed TEM image based micromagnetic simulations can directly link nanostructure of the FePt-X media with magnetic properties, boosting not only the optimization of the HAMR media but also a design of magnetic nanomaterials in general.

AB - The areal density of the heat-assisted magnetic recording (HAMR) technology has a potential to reach 4 Tb/in2. However, the bimodal grain size distribution and structural defects that are unavoidable in actual FePt-X nanogranular media must be minimized for further reduction of a jitter noise. Here we report transmission electron microscopy (TEM) image based micromagnetic simulations of the FePt-X nanogranular media in order to elucidate the role of structural defects such as [200] misalignment and {111} twins on the magnetic properties. Micromagnetic approximation of experimental out-of-plane hysteresis loops allows to evaluate micromagnetic parameters and volume fractions of the defects in MgO(6 nm)/FePt-BN(1 nm)/FePt-(BN,C,SiO2)(7 nm) granular thin films. Synchrotron XRD of the films validated that the structural defects can be accurately evaluated by the proposed approach. The developed TEM image based micromagnetic simulations can directly link nanostructure of the FePt-X media with magnetic properties, boosting not only the optimization of the HAMR media but also a design of magnetic nanomaterials in general.

KW - FePt

KW - Heat-assisted magnetic recording

KW - Micromagnetic simulation

KW - Nanostructure

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

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