Magnetic in-plane components of FePt nanogranular film on polycrystalline MgO underlayer for heat-assisted magnetic recording media

J. Wang; H. Sepehri-Amin; Y. K. Takahashi; T. Ohkubo; K. Hono

doi:10.1016/j.actamat.2019.07.017

Magnetic in-plane components of FePt nanogranular film on polycrystalline MgO underlayer for heat-assisted magnetic recording media

J. Wang^*, H. Sepehri-Amin, Y. K. Takahashi, T. Ohkubo, K. Hono

^*Corresponding author for this work

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

8 Citations (Scopus)

Abstract

A systematic study is conducted on the effect of MgO substrate/underlayer in terms of the surface roughness, grain boundary, and crystallographic texture on the magnetic in-plane components (medium noise) of the FePt-based heat-assisted magnetic recording (HAMR) media. Cross-sectional transmission electron microscope observations revealed that good (001) texture can be developed in FePt nanogranular films even when they are grow on a rough surface of a single crystal-MgO (001) substrate or across the grain boundaries of a (001)-textured polycrystalline-MgO underlayer. The misoriented FePt grains with magnetic easy axes (c-axes) tilted away from the film normal direction mainly originate from their epitaxial growth on the initially misoriented MgO underlayer grains. Micromagnetic simulation results revealed that the FePt grains with misorientation angle larger than ∼20° are attributed to the detected magnetic in-plane components. Based on these experimental results, we discuss how to improve the (001) texture of the polycrystalline underlayer as well as to develop FePt-based HAMR media with enhanced signal-to-noise ratio.

Original language	English
Pages (from-to)	1-8
Number of pages	8
Journal	Acta Materialia
Volume	177
DOIs	https://doi.org/10.1016/j.actamat.2019.07.017
Publication status	Published - 2019 Sept 15
Externally published	Yes

Keywords

Crystallographic texture
FePt
Grain boundary
In-plane component
Surface roughness

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.2019.07.017

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title = "Magnetic in-plane components of FePt nanogranular film on polycrystalline MgO underlayer for heat-assisted magnetic recording media",

abstract = "A systematic study is conducted on the effect of MgO substrate/underlayer in terms of the surface roughness, grain boundary, and crystallographic texture on the magnetic in-plane components (medium noise) of the FePt-based heat-assisted magnetic recording (HAMR) media. Cross-sectional transmission electron microscope observations revealed that good (001) texture can be developed in FePt nanogranular films even when they are grow on a rough surface of a single crystal-MgO (001) substrate or across the grain boundaries of a (001)-textured polycrystalline-MgO underlayer. The misoriented FePt grains with magnetic easy axes (c-axes) tilted away from the film normal direction mainly originate from their epitaxial growth on the initially misoriented MgO underlayer grains. Micromagnetic simulation results revealed that the FePt grains with misorientation angle larger than ∼20° are attributed to the detected magnetic in-plane components. Based on these experimental results, we discuss how to improve the (001) texture of the polycrystalline underlayer as well as to develop FePt-based HAMR media with enhanced signal-to-noise ratio.",

keywords = "Crystallographic texture, FePt, Grain boundary, In-plane component, Surface roughness",

author = "J. Wang and H. Sepehri-Amin and Takahashi, {Y. K.} and T. Ohkubo and K. Hono",

note = "Funding Information: This work was supported in part by IDEMA-ASTC, the KAKENHI Grant-in-Aid (A) (Grant No. 18H03787 ). JSPS KAKENHI Grant Number JP19K05257 , JW acknowledges NIMS for the provision of the ICYS fellowship. Publisher Copyright: {\textcopyright} 2019 Acta Materialia Inc.",

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T1 - Magnetic in-plane components of FePt nanogranular film on polycrystalline MgO underlayer for heat-assisted magnetic recording media

AU - Wang, J.

AU - Sepehri-Amin, H.

AU - Takahashi, Y. K.

AU - Ohkubo, T.

AU - Hono, K.

N1 - Funding Information: This work was supported in part by IDEMA-ASTC, the KAKENHI Grant-in-Aid (A) (Grant No. 18H03787 ). JSPS KAKENHI Grant Number JP19K05257 , JW acknowledges NIMS for the provision of the ICYS fellowship. Publisher Copyright: © 2019 Acta Materialia Inc.

PY - 2019/9/15

Y1 - 2019/9/15

N2 - A systematic study is conducted on the effect of MgO substrate/underlayer in terms of the surface roughness, grain boundary, and crystallographic texture on the magnetic in-plane components (medium noise) of the FePt-based heat-assisted magnetic recording (HAMR) media. Cross-sectional transmission electron microscope observations revealed that good (001) texture can be developed in FePt nanogranular films even when they are grow on a rough surface of a single crystal-MgO (001) substrate or across the grain boundaries of a (001)-textured polycrystalline-MgO underlayer. The misoriented FePt grains with magnetic easy axes (c-axes) tilted away from the film normal direction mainly originate from their epitaxial growth on the initially misoriented MgO underlayer grains. Micromagnetic simulation results revealed that the FePt grains with misorientation angle larger than ∼20° are attributed to the detected magnetic in-plane components. Based on these experimental results, we discuss how to improve the (001) texture of the polycrystalline underlayer as well as to develop FePt-based HAMR media with enhanced signal-to-noise ratio.

AB - A systematic study is conducted on the effect of MgO substrate/underlayer in terms of the surface roughness, grain boundary, and crystallographic texture on the magnetic in-plane components (medium noise) of the FePt-based heat-assisted magnetic recording (HAMR) media. Cross-sectional transmission electron microscope observations revealed that good (001) texture can be developed in FePt nanogranular films even when they are grow on a rough surface of a single crystal-MgO (001) substrate or across the grain boundaries of a (001)-textured polycrystalline-MgO underlayer. The misoriented FePt grains with magnetic easy axes (c-axes) tilted away from the film normal direction mainly originate from their epitaxial growth on the initially misoriented MgO underlayer grains. Micromagnetic simulation results revealed that the FePt grains with misorientation angle larger than ∼20° are attributed to the detected magnetic in-plane components. Based on these experimental results, we discuss how to improve the (001) texture of the polycrystalline underlayer as well as to develop FePt-based HAMR media with enhanced signal-to-noise ratio.

KW - Crystallographic texture

KW - FePt

KW - Grain boundary

KW - In-plane component

KW - Surface roughness

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Magnetic in-plane components of FePt nanogranular film on polycrystalline MgO underlayer for heat-assisted magnetic recording media

Abstract

Keywords

ASJC Scopus subject areas

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