Switching Field Distribution of MnGa Bit Patterned Film Fabricated by Ion Beam Irradiation

Oshima, Daiki; Kato, Takeshi; Iwata, S.

doi:10.1109/tmag.2017.2733765

Cited by 3 publications

(9 citation statements)

References 22 publications

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“…In these materials, a quite low ion dose~10 14 ions/cm 2 is sufficient to change their magnetism. We also demonstrated high-density planar BPM with a period of the bit array down to 80 nm [20,22] and HDD head flyable planar BPM by using this technique [15]. We observed that the SFD of the ion beam-patterned MnGa was~25% [22], and discussed the origins of the SFD.…”

Section: Introductionmentioning

confidence: 84%

“…We observed that the SFD of the ion beam-patterned MnGa was~25% [22], and discussed the origins of the SFD. In this article, we first review the results of ion irradiation into MnGa presented in our previous papers [20][21][22], and report the magnetization dynamics of the irradiated MnGa films to determine the origin of SFD in more detail.…”

Section: Introductionmentioning

confidence: 87%

“…This indicates the phase change from the ferromagnetic L1 0 ordered phase to a paramagnetic A1 disordered phase by the ion irradiation as shown in Figure 2 (see also Refs. [20,22]). The variation of the XRD profiles explains well the change of the magnetic properties.…”

Section: Control Of the Structure And Magnetic Properties Of Mnga Filmentioning

confidence: 99%

“…These values are normalized as the values of as-prepared MnGa to be 1. The ion dose changes the structure of MnGa from the L1 0 phase to the A1 phase, and the microstructure of the L1 0 phase surrounded by the A1 phase is expected at~1 × 10 13 ions/cm 2 as shown in the figure [22]. Figure 5 provides schematics of the fabrication process of magnetically patterned MnGa films.…”

Section: Control Of the Structure And Magnetic Properties Of Mnga Filmentioning

confidence: 99%

“…We reported that 30 keV Kr + ion implantation altered the magnetism of CrPt 3 [15][16][17][18], MnAl [19], MnGa [19][20][21][22], and MnBiCu [23] from ferromagnetic to paramagnetic according to the change of the crystal structure from the ordered to disordered phase. All of these materials exhibit a strong perpendicular magnetic anisotropy, which is an essential property for high-density BPM.…”

Section: Introductionmentioning

confidence: 99%

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Ion Irradiation for Planar Patterning of Magnetic Materials

2019

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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.

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 87%

Section: Control Of the Structure And Magnetic Properties Of Mnga Filmentioning

confidence: 99%

Section: Control Of the Structure And Magnetic Properties Of Mnga Filmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ion Irradiation for Planar Patterning of Magnetic Materials

2019

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Synthesis of hard magnetic Mn3Ga micro-islands by e-beam evaporation

Akdoğan

2017

AIP Advances

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The permanent magnet industry heavily depends on Nd-Fe-B and Sm-Co alloys because of their high-energy product and high room temperature coercivity. Main ingredient for having such superior magnetic properties compared to other known ferromagnetic materials is rare earth elements (Nd, Sm, Dy…). However recent worldwide reserve and export limitation problem of rare earths, shifted researchers’ focus to rare earth free permanent magnets. Among many alternatives (FePt, Zr2Co11, FeNi …), Mn-based alloys are the most suitable due to abundance of the forming elements and trivial formation of the necessary hard phases. In this study, Mn3Ga micro islands have been prepared. Mn3Ga owes its hard magnetic properties to tetragonal D022 phase with magnetic anisotropy energy of 2 MJ/m3. Thin films and islands of Cr/MnGa/Cr layers have been deposited on Si/SiO2 wafers using combination of e-beam and thermal evaporation techniques. Cr has been used as buffer and cover layer to protect the sample from the substrate and prevent oxidation during annealing. Annealing under Ar/H2 forming gas has been performed at 350oC for 10 min. Nano thick islands of 25, 50 and 100 μm lateral size have been produced by photolithography technique. Room temperature coercivity of 7.5 kOe has been achieved on 100 μm micro islands of Mn3Ga. Produced micro islands could be a rare earth free alternative for magnetic memory and MEMS applications.

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