First principles study of perpendicular magnetic anisotropy in thin-film Co2MnSi. (17th September 2021)

• Record Type: Journal Article
• Authors: Stuelke, Lukas; Kharel, Parashu; Shand, Paul M; Lukashev, Pavel V
• Is Part Of: Physica scripta. Volume 96:Number 12(2021)
• Publication Date: 2021-09-17
• Subjects: half metals -- spintronics -- perpendicular magnetic anisotropy -- first principles calculations; Physics -- Periodicals; 530.05
• DOI: 10.1088/1402-4896/ac2544
• Languages: English
• ISSNs: 0031-8949

Abstract

Abstract: Among different physical parameters taken into account for practical implementations in the field of spin-based electronics (spintronics), magnetocrystalline anisotropy (MCA) and spin polarization play a particularly important role. The former determines the orientation of magnetization direction, while a high degree of the latter is required for producing a spin-polarized current, a cornerstone of spintronics. Due to the miniaturization of the modern electronic devices, one often needs to consider physical effects associated with reduced geometry. In particular, in magnetic thin-film materials, MCA may take a form of perpendicular magnetic anisotropy (PMA), which could be beneficial, e.g. in magnetoresistive random-access memory (MRAM). Yet, combining PMA with half-metallicity may be a challenging task, since the latter is usually destroyed in thin-film geometry (e.g., due to the emergence of surface states), while the former is most pronounced in reduced geometry, because of the contribution to MCA from surface anisotropy. Here, we theoretically explore the nature of PMA in the thin-film full Heusler alloy Co2 MnSi. This material was extensively studied in the past, and it is one of the first compounds for which a half-metallic electronic structure was experimentally confirmed. In addition, it has been reported that this alloy may exhibit perpendicular magnetic anisotropy in thin-film geometry. Here, by analyzing the site-projected magnetocrystalline anisotropy energy (MAE), we confirm that both PMA and surface half-metallicity are very sensitive to the termination surface and mechanical strain. In particular, while MnSi-termination under compressive strain may retain both 100% spin-polarization and out-of-plane magnetization orientation, Co-termination has a detrimental impact on both. These results may serve as a guide for practical applications in the field of spin-based electronics.