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arXiv · 1908.07804

Half-metallic ferromagnetism and Ru-induced localization in quaternary Heusler alloy CoRuMnSi

Y. Venkateswara·Deepika Rani·K. G. Suresh·Aftab Alam
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Abstract

We report a combined theoretical and experimental investigation of half-metallic ferromagnetism in equiatomic quaternary Heusler alloy CoRuMnSi. Room temperature XRD analysis reveals that the alloy crystallizes in L21 disorder instead of pristine Y-type structure due to 50% swap disorder between the tetrahedral sites, i.e., Co and Ru atoms. Magnetization measurements reveal a net magnetization of 4 $\mu_B$ with Curie temperature of ~780 K. Resistivity measurement reveals the presence of localization effect below 35 K while above 100 K, a linear dependence is observed. Resistivity behavior indicates the absence of single magnon scattering, which indirectly supports the half-metallic nature. The majority spin band near the Fermi level clearly indicates the overlap of flat eg bands with sharply varying conduction bands that are responsible for the localization. In-depth analysis of the projected atomic d-orbital character of band structure reveals unusual bonding, giving rise to the flat eg bands purely arising out of Ru ions. Co-Ru swap disorder calculations indicate the robustness of half-metallic nature, even when the structure changes from Y-type to L21-type, with no major change in the net magnetization of the system. Thus, robust half-metallic nature, stable structure, and high Curie temperature make this alloy quite a promising candidate to be used as a source of highly spin-polarized currents in spintronic applications.

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Y. Venkateswara, Deepika Rani, K. G. Suresh, Aftab Alam. 2019-08-21. Half-metallic ferromagnetism and Ru-induced localization in quaternary Heusler alloy CoRuMnSi. https://doi.org/10.1016/j.jmmm.2020.166536

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