Investigation of binary Co$_{2}$X (X = In, Si, Sb, Sn, Ga) half-Heusler alloys


Abstract: The electronic structure and mechanical properties of some cobalt-based binary half-Heusler alloys Co$_{2}$X (X = In, Si, Sb, Sn, Ga) have been investigated using the density functional theory approach. The site preference by cobalt and X is similar to the traditional half-Heusler structure. The results showed that Co$_{2}$Si is not a half-metal but rather an n-type degenerate semiconductor. The compounds Co$_{2}$Ga, Co$_{2}$Sb, and Co$_{2}$Sn are thermodynamically unstable and Co$_{2}$In is elastically unstable. With much care given to the lattice size, half metallicity is readily predicted in Co$_{2}$In, Co$_{2}$Ga, Co$_{2}$Sn, and Co$_{2}$Sb. All the compounds showed directional bonding and they should exhibit high strength. The trend is that the low valence main group elements are likely to form half metals more readily in a binary half-Heusler alloy than the high valence main group elements.

Keywords: Cobalt, half-Heusler, spintronic, density of states, n-type degenerate

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