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Magnetic materials with negative spin polarization have attracted attention for their potential to increase the design freedom of spintronic devices. This study investigated the effects of off-stoichiometry on the atomic ordering, microstructure, and magneto-transport properties in Mn2+xV1-xGa (x = −0.2, 0, +0.2) Heusler alloy films, which are predicted to have large negative spin polarization derived from a pseudo band gap in the majority spin channel. The Mn2+xV1-xGa films epitaxially grown on MgO(001) substrates exhibits a higher degree of B2 and L21 order with increasing the Mn concentration. A high-quality L21-ordered film was achieved in the Mn-rich composition with B2 and L21 order of 0.97 and 0.86, respectively, and a saturation magnetization of 1.4 μB/f.u, which agrees the Slater-Pauling rule. Scanning transmission electron microscopy observations showed that B2 and L21 phases coexist in Mn-poor and stoichiometric films, while the L21 phase is dominant in the Mn-rich film with small amounts of Mn–V and Mn–Ga disorders, as revealed by laboratory and anomalous X-ray diffraction. Combined first-principles calculations and anisotropic magnetoresistance analysis confirm that the addition of excess Mn preserves the high spin polarization by suppressing the formation of deleterious anti-sites of V atoms occupying Mn sites. Therefore, the Mn-rich composition is promising for negatively spin-polarized charge injection in Mn2VGa-based spintronic applications.

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• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

Keyword: Heusler alloy, Atomic order, Magnetic properties, Spintronics, First-principles calculations

Date published: 2024-06-13

Publisher: Elsevier

Journal:

• ACTA MATERIALIA

Funding:

• JSPS 21K20434 (スピントルク発振素子の磁化ダイナミクス解明のための新規計測技術開発)
• JSPS 23K03934 (負のスピン分極ハーフメタル材料の探索と超高出力スピントルク発振素子への応用)
• JSPS 19K05249 (超高周波ワイヤレス給電に向けたスピンを介した分子運動－電気伝導変換の理論的研究)
• MEXT JPMXP1122715503 (データ創出・活用型マテリアル研究開発プロジェクト事業)
• ASRC

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.4563

First published URL: https://doi.org/10.1016/j.actamat.2024.120110

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Updated at: 2025-06-24 08:30:47 +0900

Published on MDR: 2025-06-24 08:20:46 +0900