Abstract
Based on first-principle FLAPW-GGA calculations, we have investigated the systematic trends in structural and electronic properties of a newly discovered group of ThCr 2Si 2-like arsenides: SrRu 2As 2, BaRu 2As 2, SrRh 2As 2 and BaRh 2As 2. Our results show that the replacement of an alkaline earth metal (Sr ↔ Ba) and 4d metal (Ru ↔ Rh) leads to various types of anisotropic deformations of the crystal structure caused by strong anisotropy of inter-atomic bonds. The band structure, density of states and Fermi surfaces have been evaluated and discussed. Appreciable changes in the near-Fermi bands and the Fermi surface topology found as going from (Sr,Ba)Ru 2As 2 to (Sr,Ba)Rh 2As 2 reflect the growth of the 3D-like type of dispersion for these systems, which is accompanied by an increase in the near-Fermi density of states. The inter-atomic bonding in (Sr,Ba)(Ru,Rh) 2As 2 phases adopts a complex anisotropic character, where the bonding in [ (Ru,Rh) 2As 2] blocks is of a mixed metallic–ionic-covalent type whereas between adjacent [ (Ru,Rh) 2As 2] blocks and (Sr, Ba) atomic sheets, ionic interactions emerge; thus these systems may be classified as ionic metals.
Published Version
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