The pseudochiral Fermi surface of α-RuI₃

In continuation of research into RuCl₃ and RuBr₃ as potential quantum spin liquids, a phase with unique magnetic order characterised by long-range quantum entanglement and fractionalised excitations, the compound RuI₃ has been recently synthesised. Here, we show RuI₃ is a moderately correlated metal with two bands crossing the Fermi level, implying the absence of any quantum spin liquids phase. We find that the Fermi surface as measured or calculated for a 2D (k _x, k _y) slice at any k _z lacks mirror symmetry, i.e. is pseudochiral. We link this phenomenon to the ABC stacking in the R 3 ¯ space group of α-RuI₃, which is achiral but lacks any mirror or glide symmetries. We further provide a formal framework for understanding when such a pseudochiral electronic structure may be observed.