Light-element and purely charge-based topological materials

Abstract We examine a class of Hamiltonians characterized by interatomic, interorbital even–odd parity hybridization as a model for a family of topological insulators without the need for spin–orbit coupling. Non-trivial properties of these materials are exemplified by studying the topologically-protected edge states of s - p hybridized alkali and alkaline earth atoms in one and two-dimensional lattices. In 1D the topological features are analogous to the canonical Su–Schrieffer–Heeger model but, remarkably, occur in the absence of dimerization. Alkaline earth chains, with Be standing out due to its gap size and near particle-hole symmetry, are of particular experimental interest since their Fermi energy without doping lies directly at the level of topological edge states. Similar physics is demonstrated to occur in a 2D honeycomb lattice system of s - p bonded atoms, where dispersive edge states emerge. Lighter elements are predicted using this model to host topological states in contrast to spin–orbit coupling-induced band inversion favoring heavier atoms.