Electronic instabilities in compounds with hexagonal nets

Abstract

Ab initio band structure calculations on some compounds with either hexagonal or triangular nets in their crystal structures are presented. The view taken is that electronic instabilities as manifested in certain visualisations of the electronic structures can be indicative of the presence of interesting ground states including superconductivity. The Fermi surfaces of known hexagonal superconductors such as TaS ₂ , Li _0.5 NbO ₂ and the new superconductor, Li-doped β-ZrNCl have been examined for such patterns of instabilities. Similar patterns in the Fermi surfaces of other compounds with related structural motifs but of different compositions and/or electron counts have then been sought. Amongst the compounds so analysed are the metallic delafossite PdCoO ₂ , and SrPdP with the ZrBeSi structure.