Effects of film composition and substrate orientation on the structure and the magnetic properties of Fe-Co-B alloy films formed on MgO single-crystal substrates

Asai, Yugo; Ohtake, Mitsuru; Kawai, Takeshi; Futamoto, Masaaki

doi:10.3938/jkps.63.733

Cited by 4 publications

(8 citation statements)

References 4 publications

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“…21 interfaces. The crystallographic orientation relationships observed in the present study is similar to those reported for the Fe-based alloy films with bcc(110) orientation formed on MgO(111) substrates 15,16) . …”

Section: Methodssupporting

confidence: 78%

Effect of Si/Fe Composition, Substrate Temperature, and Substrate Orientation on the Structure and Magnetic Properties of Fe-Si Alloy Film

et al. 2016

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Fe100-xSix (x = 0, 2, 6, 10 at. %) alloy films are prepared on MgO single-crystal substrates of (001), (110), and (111) orientations at temperatures ranging between room temperature and 600 °C by using a radio-frequency magnetron sputtering system. The film growth behavior, the crystallographic properties, and the magnetic properties are systematically investigated. Fe-Si(001) single-crystal films with bcc structure are formed on MgO (001) substrates. The Fe-Si films deposited on MgO(110) substrates consist of epitaxial bcc(211) bi-crystals whose orientations are rotated around the film normal by 180° each other. Fe-Si films grow epitaxially on MgO(111) substrates with two types of bcc(110) variant whose crystallographic orientations are similar to the Nishiyama-Wasserman and the Kurdjumov-Sachs relationships. The orientation dispersion of Fe-Si film decreases with decreasing the Si composition, with increasing the substrate temperature, and with decreasing the index of the substrate crystallographic plane. The Fe-Si films deposited on MgO (001) and (110) show in-plane magnetic anisotropies reflecting the magnetocrystalline anisotropies of bulk Fe-Si alloy crystals. The Fe-Si films deposited on MgO(111) show nearly isotropic in-plane magnetic anisotropies that possibly come from the multiple variant structure. The coercivity decreases with increasing the Si composition and with decreasing the substrate temperature.

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Section: Methodssupporting

confidence: 78%

Effect of Si/Fe Composition, Substrate Temperature, and Substrate Orientation on the Structure and Magnetic Properties of Fe-Si Alloy Film

et al. 2016

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“…Besides the discussed lattice preferences of boron, amorphization of the Fe-Co lattice is expected to begin at a certain B content. Depending on the film preparation conditions, amorphous Fe-Co-B phases were reported at B concentrations of e. g. 7.5 6 , 15 7 or 22 at% 5 .…”

Section: Introductionmentioning

confidence: 99%

“…Fe-Co exhibits one of the highest magnetisations among all magnetic materials [1,2] and is thus very attractive for applications [3]. Fe-Co-B alloys are well known as soft magnetic materials due to the glass-forming ability of boron [4][5][6][7]. In such amorphous materials the magnetocrystalline anisotropy is suppressed.…”

Section: Introductionmentioning

confidence: 99%

“…Since both, soft and hard magnets require a high magnetisation, Fe-Co [1,2] is the focus of research. For soft magnetic materials, the magnetic anisotropy should be as low as possible, which is commonly achieved by reducing the grain size towards nanocrystalline or even amorphous materials [5,7,9]. Aiming at hard magnetic properties, a crystalline structure is essential as a magnetocrystalline anisotropy can favour particular directions of magnetisation.…”

Section: Introductionmentioning

confidence: 99%

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From soft to hard magnetic Fe–Co–B by spontaneous strain: a combined first principles and thin film study

Reichel

Schultz

Pohl

et al. 2015

J. Phys.: Condens. Matter

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In order to convert the well-known Fe-Co-B alloy from a soft to a hard magnet, we propose tetragonal strain by interstitial boron. Density functional theory reveals that when B atoms occupy octahedral interstitial sites, the bcc Fe-Co lattice is strained spontaneously. Such highly distorted Fe-Co is predicted to reach a strong magnetocrystalline anisotropy which may compete with shape anisotropy. To probe this theoretical suggestion experimentally, epitaxial films are examined. A spontaneous strain up to 5% lattice distortion is obtained for B content up to 4 at%, which leads to uniaxial anisotropy constants exceeding 0.5 MJ m(-3). However, a further addition of B results in a partial amorphisation, which degrades both anisotropy and magnetisation.

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“…Fe-Co and Fe-Co-B alloys with bcc structure are typical soft magnetic materials with high saturation magnetizations and have been frequently used as the electrode material. However, the crystallographic structure of Fe-Co-B film is affected by the B content 3,4) and the formation condition like annealing temperature [5][6][7][8] . Fe-Co-B film with a higher B content deposited at a lower substrate temperature tends to involve amorphous.…”

Section: Introductionmentioning

confidence: 99%

Structure Analysis of Fe-Co and Fe-Co-B Alloy Thin Films Formed on MgO(001) Substrate

et al. 2017

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Fe-Co and Fe-CoB alloy films of 40 nm thickness are prepared by sputtering on MgO(001) single-crystal substrates using alloy targets of (Fe0.7Co0.3)100-xBx (x = 0, 5, 10, 15 at. %) by varying the substrate temperature from room temperature (RT) to 600 °C. The film structure is investigated by reflection high-energy electron diffraction and out-of-plane, in-plane, and pole-figure X-ray diffractions. Preparation condition of epitaxial film is found to depend on the B content and the substrate temperature. Epitaxial (Fe0.7Co0.3)100-xBx films are obtained at the investigated temperatures for the B contents lower than 5 at. %, whereas films with the B contents of 10 and 15 at. % grow epitaxially at temperatures higher than 400 and 600 °C, respectively. Single-crystal films of bcc(001) orientation are formed at temperatures higher than RT, 200, 400, and 600 °C for the B contents of 0, 5, 10, and 15 at. %, respectively. As the substrate temperature decreases, the epitaxial films with B contents of 5-15 at. % tend to involve four types of bcc(122) variant whose orientations are rotated around the film normal by 90° each other. The (Fe0.7Co0.3)90B10 film deposited at RT and the (Fe0.7Co0.3)85B15 films deposited at temperatures from RT to 200 °C are found to be consisting of bcc polycrystal and amorphous, respectively. The structure is thus determined to vary in the order of bcc(001) single-crystal => bcc(001) and bcc(122) epitaxial crystals => bcc polycrystal => amorphous with increasing the B content and with decreasing the substrate temperature. The lattices of single-crystal Fe-Co (x = 0 at. %) and Fe-CoB (x = 5-15 at. %) films are respectively expanded along the in-plane and the perpendicular directions. The single-crystal Fe-Co films show in-plane magnetic anisotropies with the easy magnetization directions of bcc[100] and bcc[010], which is reflecting the magnetocrystalline anisotropy of bulk bcc-Fe70Co30 alloy. On the contrary, the single-crystal Fe-CoB films show almost isotropic in-plane magnetic properties and weak perpendicular anisotropies, which is possibly caused by an influence of lattice deformation along the perpendicular direction.

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Effects of film composition and substrate orientation on the structure and the magnetic properties of Fe-Co-B alloy films formed on MgO single-crystal substrates

Cited by 4 publications

References 4 publications

Effect of Si/Fe Composition, Substrate Temperature, and Substrate Orientation on the Structure and Magnetic Properties of Fe-Si Alloy Film

Effect of Si/Fe Composition, Substrate Temperature, and Substrate Orientation on the Structure and Magnetic Properties of Fe-Si Alloy Film

From soft to hard magnetic Fe–Co–B by spontaneous strain: a combined first principles and thin film study

Structure Analysis of Fe-Co and Fe-Co-B Alloy Thin Films Formed on MgO(001) Substrate

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