Structural and magnetic properties of CoIrMnAl equiatomic quaternary Heusler alloy epitaxial films designed using first-principles calculations

JOURNAL OF ALLOYS AND COMPOUNDS

卷:868

Article

Monma, Ren^1,2  Roy, Tufan³  Suzuki, Kazuya^2,4  Tsuchiya, Tomoki^4,5  Tsujikawa, Masahito^3,4  Mizukami, Shigemi^2,4,5  Shirai, Masafumi^3,4,5 

[1] Tohoku Univ, Grad Sch Engn, Dept Appl Phys, Aoba 06-05, Sendai, Miyagi 9808579, Japan

[2] Tohoku Univ, WPI Adv Inst Mat Res AIMR, 2-1-1 Katahira, Sendai, Miyagi 9808577, Japan

[3] Tohoku Univ, Res Inst Elect Commun, Sendai, Miyagi 9808577, Japan

[4] Tohoku Univ, Ctr Spintron Res Network CSRN, Sendai, Miyagi 9808577, Japan

[5] Tohoku Univ, Ctr Sci & Innovat Spintron CSIS, Core Res Cluster CRC, Sendai, Miyagi 9808577, Japan

关键词: Half metals;    Magnetically ordered materials;    Thin films;    Vapor deposition;    Magnetization;    Computer simulations;   

DOI  :  10.1016/j.jallcom.2021.159175

来源: Elsevier

【 摘 要 】

MgO-barrier magnetic tunnel junctions with half-metallic Heusler alloy electrodes have attracted con-siderable attention for spintronics applications. However, there remain a couple of issues related to materials that should be resolved before practical use. Recently, quarterly equiatomic Heusler alloys have attracted attention as advanced Heusler alloys. CoIrMnZ (Z = Al, Si, Ga, and Ge) half-metallic Heusler alloys were designed and predicted to have moderate Curie temperatures and to be lattice-matched with the MgO barrier, which is advantageous compared to traditional Co-2 Heusler alloys T. T [T. Roy et al., J. Magn. Magn. Mater. 498 (2020) 166092]. Here, we experimentally investigated the structure and magnetic properties of thin films composed of one of these alloys, CoIrMnAl, fabricated by sputtering deposition. We successfully obtained films with the B2 chemical ordering, even without a post-annealing process. The lattice constants for the films annealed at 500-600 degrees C were approximately equal to the predicted values. The magnetization at 10 K was close to 500 kA/m, and the Curie temperature was approximately 400 K, which were approximately 70% of the values predicted for the fully ordered structure. The magnetic properties observed in the B2-ordered films were well explained by ferrimagnetism that appeared in the B2-ordered CoIrMnAl with full-swap disorders of Co-Ir and Mn-Al and almost full-swap disorder of Co-Mn, which was predicted from the first-principles calculations. (C) 2021 Elsevier B.V. All rights reserved.

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