Formation of Flat FePd-Alloy Epitaxial Thin Film with L10 Ordered Structure by Low-Temperature Deposition Followed by Annealing

Itabashi, Akira; Ohtake, Mitsuru; Ouchi, Shouhei; Kirino, Fumiyoshi; Futamoto, Masaaki

doi:10.3379/msjmag.1310r002

Cited by 6 publications

(4 citation statements)

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“…Films without annealing were also prepared. The details of film preparation were similar to our previous studies [8], [9]. The surface morphology was observed by atomic force microscopy (AFM).…”

Section: Methodsmentioning

confidence: 98%

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Crystal Orientation, Order Degree, and Surface Roughness of FePd-Alloy Film Formed on MgO(001) Substrate

et al. 2015

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FePd alloy films of 1 to 500 nm thicknesses are prepared on MgO(001) single-crystal substrates by employing a two-step method consisting of low-temperature deposition at 200 °C followed by high-temperature annealing at 600 °C. The influences of film thickness on the crystallographic orientation, the degree of L1 0 ordering, the magnetic property, and the surface roughness are systematically investigated. FePd(001) single-crystal films with disordered structure grow epitaxially on the substrates at 200 °C. The in-plane lattice is expanded to accommodate the lattice misfit between film and substrate (-9%). The distortion is decreased with increasing the thickness. When the films are annealed at 600 °C, transformation to L1 0 phase occurs. The films thinner than 40 nm consist of L1 0 (001) variant with the c-axis normal to the substrate surface, where the transformation along the perpendicular direction is preferentially taking place. On the contrary, the films thicker than 100 nm involve L1 0 (100) and L1 0 (010) variants whose c-axes are lying in the film plane and rotated around the film normal by 90° each other. The volume ratio of L1 0 (001) variant decreases to 0.22, as the thickness increases up to 500 nm. The order degrees of films thinner than 40 nm are 0.6-0.7. With further increasing the thickness, the order degree decreases. The lattice deformation in disordered FePd film before annealing is effective in enhancing L1 0 ordering and aligning the c-axis perpendicular to the substrate surface. The easy magnetization direction varies from perpendicular to in-plane, as the thickness increases from 100 to 500 nm. The magnetic anisotropy is affected by the crystal orientation and the order degree. The films thinner than 2 nm have island-like surfaces, where condensation of deposited atoms on substrate is taking place during the annealing process. When the thickness is increased beyond 10 nm, flat surface is kept before and after annealing.Index Terms-c-axis orientation, FePd alloy single-crystal film, L1 0 structure, order degree, surface morphology.

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Section: Methodsmentioning

confidence: 98%

“…In our previous studies [8], [9], FePd films of 40 nm thickness were prepared on MgO(001) substrates by two different methods. One was a one-step method consisting of high-temperature deposition at 600 °C, where L1 0 crystals nucleated on the substrates.…”

Section: Introductionmentioning

confidence: 99%

Crystal Orientation, Order Degree, and Surface Roughness of FePd-Alloy Film Formed on MgO(001) Substrate

et al. 2015

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“…Considering that the film morphology is influenced during the film deposition process, a two-step process technique consisting of a low temperature film deposition followed by a high temperature annealing for L10 ordering has been investigated to prepare an L10 ordered film with improved surface flatness 153,174,175,177) . Figure 20 compares the surface structures of FePd thin films of 2 -40 nm thicknesses observed by atomic force microscopy (AFM).…”

Section: Methodsmentioning

confidence: 99%

Development of Media Nanostructure for Perpendicular Magnetic Recording

Futamoto

Ohtake

2017

J. Magn. Soc. Jpn.

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The review covers the research and development of perpendicular media nanostructure focusing on the recording layer. The recording layer material includes the Co-alloys with hcp structure, the magnetic multilayers, and the alloys with ordered structures that have high magneto-crystalline anisotropies (Ku). The technologies of underlayer or interlayer for aligning the easy magnetization axis of magnetic crystal grain perpendicular to the film plane are briefly reviewed including the high Ku magnetic materials for future recording media.Observations of compositional and magnetization structures in sub-µm scale have played important roles in improving the recording layer. Typical data on these characteristics are explained in relation to the media structure improvements. Considering that high Ku magnetic materials will be employed in future recording media, basic experimental results related in controlling the easy magnetization axis and in keeping the surface flatness of L10-ordered magnetic materials are explained. Future possibilities for increasing the areal density beyond 1 Tb/in 2 by improving the magnetic material and the nanostructure of recording layer are also discussed.

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“…[3][4][5] The authors have shown that a twostep process consisting of low temperature film formation followed by high temperature annealing is effective for the preparation of L1 0 -FePt thin film with an improved surface flatness. 6,7 When an Fe-Pt alloy thin film is formed on an oxide substrate such as MgO(001) single-crystal at low temperatures where the impinging atom migration is limited, the film morphology tends to be continuous with small surface undulations. By heating the film at a higher temperature, migration of atoms within the film proceeds to form an L1 0 -ordered structure keeping the film morphology.…”

Section: Introductionmentioning

confidence: 99%

Preparation of c-axis perpendicularly oriented ultra-thin L1-FePt films on MgO and VN underlayers

2018

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Ultra-thin L10-FePt films of 2 nm average thickness are prepared on (001) oriented MgO and VN underlayers epitaxially grown on base substrate of SrTiO3(001) single crystal. Detailed cross-sectional structures are observed by high-resolution transmission electron microscopy. Continuous L10-FePt(001) thin films with very flat surface are prepared on VN(001) underlayer whereas the films prepared on MgO(001) underlayer consist of isolated L10-FePt(001) crystal islands. Presence of misfit dislocation and lattice bending in L10-FePt material is reducing the effective lattice mismatch with respect to the underlayer to be less than 0.5 %. Formation of very flat and continuous FePt layer on VN underlayer is due to the large surface energy of VN material where de-wetting of FePt material at high temperature annealing process is suppressed under a force balance between the surface and interface energies of FePt and VN materials. An employment of underlayer or substrate material with the lattice constant and the surface energy larger than those of L10-FePt is important for the preparation of very thin FePt epitaxial thin continuous film with the c-axis controlled to be perpendicular to the substrate surface.

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Formation of Flat FePd-Alloy Epitaxial Thin Film with L10 Ordered Structure by Low-Temperature Deposition Followed by Annealing

Cited by 6 publications

References 1 publication

Crystal Orientation, Order Degree, and Surface Roughness of FePd-Alloy Film Formed on MgO(001) Substrate

Crystal Orientation, Order Degree, and Surface Roughness of FePd-Alloy Film Formed on MgO(001) Substrate

Development of Media Nanostructure for Perpendicular Magnetic Recording

Preparation of c-axis perpendicularly oriented ultra-thin L1-FePt films on MgO and VN underlayers

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