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Enhanced half-metallicity of off-stoichiometric quaternary Heusler alloy Co-2(Mn, Fe)Si investigated through saturation magnetization and tunneling magnetoresistance

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この文献へのリンクには次のURLを使用してください:http://hdl.handle.net/2115/61479

タイトル: Enhanced half-metallicity of off-stoichiometric quaternary Heusler alloy Co-2(Mn, Fe)Si investigated through saturation magnetization and tunneling magnetoresistance
著者: Moges, Kidist 著作を一覧する
Honda, Yusuke 著作を一覧する
Liu, Hong-xi 著作を一覧する
Uemura, Tetsuya 著作を一覧する
Yamamoto, Masafumi 著作を一覧する
Miura, Yoshio 著作を一覧する
Shirai, Masafumi 著作を一覧する
発行日: 2016年 4月 4日
出版者: American Physical Society (APS)
誌名: Physical Review B
巻: 93
号: 13
開始ページ: 134403-1
終了ページ: 134403-15
出版社 DOI: 10.1103/PhysRevB.93.134403
抄録: We investigated the factors that critically affect the half-metallicity of the quaternary Heusler alloy Co2(Mn, Fe)Si (CMFS) by examining the film composition dependence of the saturation magnetization per formula unit, mu(s), of CMFS thin films and the tunneling magnetoresistance (TMR) ratio of CMFS/MgO/CMFS magnetic tunnel junctions (MTJs). We also investigated the origin of the giant TMR ratio of up to 2610% at 4.2 K (429% at 290 K) obtained for CMFS MTJs with Mn-rich, lightly Fe-doped CMFS electrodes. Co antisites at the nominal Mn/Fe sites (Co-Mn/Fe antisites) can consistently explain the mu(s) for (Mn + Fe)-deficient CMFS thin films being lower than the half-metallic Z(t) - 24 value and the TMR ratio for MTJs with (Mn + Fe)-deficient CMFS electrodes being lower than that for MTJs with (Mn+ Fe)-rich CMFS electrodes. It was revealed that the Co-Mn/Fe antisite is detrimental to the half-metallicity of the CMFS quaternary alloy, as it is in the Co2MnSi (CMS) ternary alloy. It was also shown that (Mn + Fe)-rich compositions are critical to suppressing these harmful antisites and to retaining the half-metallic electronic state. In addition, a relatively small Fe ratio, rather than a large one, in the total (Mn + Fe) composition led to a more complete half-metallic electronic state. Half-metallicity was more strongly enhanced by increasing the Mn composition in Mn-rich, lightly Fe-doped CMFS than in Mn-rich CMS. This phenomenon is the cause of the giant TMR ratio recently reported for CMFS MTJs. Our findings indicate that the approach to controlling off-stoichiometry and film composition is promising for fully utilizing the half-metallicity of quaternary CMFS thin films as spin source materials.
Rights: ©2016 American Physical Society
資料タイプ: article
URI: http://hdl.handle.net/2115/61479
出現コレクション:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

提供者: 山本 眞史

 

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