Magnetic characteristics and nanostructures of FePt granular films with GeO2 segregant

Takuya Ono; Tomohiro Moriya; Masatoshi Hatayama; Kaoru Tsumura; Nobuaki Kikuchi; Satoshi Okamoto; Osamu Kitakami; Takehito Shimatsu

doi:10.1063/1.4973473

Magnetic characteristics and nanostructures of FePt granular films with GeO₂ segregant

Takuya Ono, Tomohiro Moriya, Masatoshi Hatayama, Kaoru Tsumura, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

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

8 Citations (Scopus)

Abstract

To realize a granular film composed of L1₀-FePt grains with high uniaxial magnetic anisotropy energy, K_u, and segregants for energy-assisted magnetic recording, a FePt-GeO₂/FePt-C stacked film was investigated in the engineering process. The FePt-GeO₂/FePt-C stacked film fabricated at a substrate temperature of 450 °C realized uniaxial magnetic anisotropy, Kugrain, of about 2.5 × 10⁷erg/cm³, which is normalized by the volume fraction of FePt grains, and a granular structure with an averaged grain size of 7.7 nm. As the thickness of the FePt-GeO₂ upper layer was increased to 9 nm, the K_u values were almost constant. That result differs absolutely from the thickness dependences of the other oxide segregant materials such as SiO₂ and TiO₂. Such differences on the oxide segregant are attributed to their chemical bond. The strong covalent bond of GeO₂ is expected to result in high K_u of the FePt-GeO₂/FePt-C stacked films.

Original language	English
Article number	022402
Journal	Applied Physics Letters
Volume	110
Issue number	2
DOIs	https://doi.org/10.1063/1.4973473
Publication status	Published - 2017 Jan 9

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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title = "Magnetic characteristics and nanostructures of FePt granular films with GeO2 segregant",

abstract = "To realize a granular film composed of L10-FePt grains with high uniaxial magnetic anisotropy energy, Ku, and segregants for energy-assisted magnetic recording, a FePt-GeO2/FePt-C stacked film was investigated in the engineering process. The FePt-GeO2/FePt-C stacked film fabricated at a substrate temperature of 450 °C realized uniaxial magnetic anisotropy, Kugrain, of about 2.5 × 107erg/cm3, which is normalized by the volume fraction of FePt grains, and a granular structure with an averaged grain size of 7.7 nm. As the thickness of the FePt-GeO2 upper layer was increased to 9 nm, the Ku values were almost constant. That result differs absolutely from the thickness dependences of the other oxide segregant materials such as SiO2 and TiO2. Such differences on the oxide segregant are attributed to their chemical bond. The strong covalent bond of GeO2 is expected to result in high Ku of the FePt-GeO2/FePt-C stacked films.",

author = "Takuya Ono and Tomohiro Moriya and Masatoshi Hatayama and Kaoru Tsumura and Nobuaki Kikuchi and Satoshi Okamoto and Osamu Kitakami and Takehito Shimatsu",

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AU - Ono, Takuya

AU - Moriya, Tomohiro

AU - Hatayama, Masatoshi

AU - Tsumura, Kaoru

AU - Kikuchi, Nobuaki

AU - Okamoto, Satoshi

AU - Kitakami, Osamu

AU - Shimatsu, Takehito

PY - 2017/1/9

Y1 - 2017/1/9

N2 - To realize a granular film composed of L10-FePt grains with high uniaxial magnetic anisotropy energy, Ku, and segregants for energy-assisted magnetic recording, a FePt-GeO2/FePt-C stacked film was investigated in the engineering process. The FePt-GeO2/FePt-C stacked film fabricated at a substrate temperature of 450 °C realized uniaxial magnetic anisotropy, Kugrain, of about 2.5 × 107erg/cm3, which is normalized by the volume fraction of FePt grains, and a granular structure with an averaged grain size of 7.7 nm. As the thickness of the FePt-GeO2 upper layer was increased to 9 nm, the Ku values were almost constant. That result differs absolutely from the thickness dependences of the other oxide segregant materials such as SiO2 and TiO2. Such differences on the oxide segregant are attributed to their chemical bond. The strong covalent bond of GeO2 is expected to result in high Ku of the FePt-GeO2/FePt-C stacked films.

AB - To realize a granular film composed of L10-FePt grains with high uniaxial magnetic anisotropy energy, Ku, and segregants for energy-assisted magnetic recording, a FePt-GeO2/FePt-C stacked film was investigated in the engineering process. The FePt-GeO2/FePt-C stacked film fabricated at a substrate temperature of 450 °C realized uniaxial magnetic anisotropy, Kugrain, of about 2.5 × 107erg/cm3, which is normalized by the volume fraction of FePt grains, and a granular structure with an averaged grain size of 7.7 nm. As the thickness of the FePt-GeO2 upper layer was increased to 9 nm, the Ku values were almost constant. That result differs absolutely from the thickness dependences of the other oxide segregant materials such as SiO2 and TiO2. Such differences on the oxide segregant are attributed to their chemical bond. The strong covalent bond of GeO2 is expected to result in high Ku of the FePt-GeO2/FePt-C stacked films.

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