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Crystals 2019, 9(1), 27; https://doi.org/10.3390/cryst9010027

Ion Irradiation for Planar Patterning of Magnetic Materials

1
Department of Electronics, Nagoya University Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
2
Institute of Materials and Systems for Sustainability, Nagoya University Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
*
Author to whom correspondence should be addressed.
Received: 26 November 2018 / Revised: 25 December 2018 / Accepted: 26 December 2018 / Published: 4 January 2019
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Abstract

Kr+ ion dose dependence of the magnetic properties of MnGa films and the fabrication of planar-patterned MnGa films by the local ion irradiation technique were reviewed. The magnetization and perpendicular anisotropy of the MnGa vanished at an ion dose of 1 × 1014 ions/cm2 due to the phase change of the MnGa from ferromagnetic L10 to paramagnetic A1 phase. The average switching field Hsw of the planar-patterned MnGa increased with decreasing the bit size, implying low bit edge damage in the patterned MnGa, whereas a rather large switching field distribution (SFD) of 25% was confirmed for a bit size of ~40 nm. Time resolved magneto-optical Kerr effect measurements revealed that as-prepared MnGa exhibits an effective anisotropy field Hkeff = 20 kOe, its distribution ΔHkeff = 200 Oe, and Gilbert damping α = 0.008. The ion-irradiated MnGa films exhibited larger Hkeff = 22–23 kOe than that of the MnGa before the ion dose. Thus, ion irradiation does not decrease the perpendicular anisotropy, which suggests a small bit edge in the patterned MnGa. ΔHkeff increased from 0.2 kOe to 3 kOe, whereas the length of disorder in the film ξ decreased from 10 nm to 3 nm by ion irradiation. View Full-Text
Keywords: ion irradiation; bit patterned media; magnetic recording; phase change; surface flatness ion irradiation; bit patterned media; magnetic recording; phase change; surface flatness
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Kato, T.; Oshima, D.; Iwata, S. Ion Irradiation for Planar Patterning of Magnetic Materials. Crystals 2019, 9, 27.

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