The electronic structure of intertwined kagome, honeycomb, and triangular sublattices of the intermetallics MCo2Al9 (M = Sr, Ba)

Abstract

Intermetallics are an important playground to stabilize a large variety of physical phenomena, arising from their complex crystal structure. The ease of their chemical tunabilty makes them suitable platforms to realize targeted electronic properties starting from the symmetries hidden in their unit cell. Here, we investigate the family of the recently discovered intermetallics M Co2Al9 (M = Sr, Ba) and we unveil their electronic structure. By using angle-resolved photoelectron spectroscopy and density functional theory calculations, we discover the existence of Dirac-like dispersions as ubiquitous features in this family, coming from the hidden kagome and honeycomb symmetries embedded in the unit cell. Finally, from calculations, we expect that the spin-orbit coupling is responsible for opening energy gaps in the electronic structure spectrum, which also affects the majority of the observed Dirac-like states. Our study constitutes an experimental observation of the electronic structure of M Co2Al9 and proposes these systems as hosts of Dirac-like physics with intrinsic spin-orbit coupling. The latter effect suggests M Co2Al9 as a future platform for investigating the emergence of nontrivial topology.