Time-reversal symmetric topological superconductivity in Machida-Shibata lattices

Recent experiments engineered special spin-degenerate Andreev bound states in atomic cages of adatoms on superconductors, the Machida-Shibata states, a promising building block for quantum matter. Here, we investigate the formation of time-reversal symmetric bands by hybridizing multiple such states and analyzing their electronic topological properties assuming small on-site electron repulsion. The low-energy theory shows that competing emerging singlet and triplet superconducting pairings drive the formation of topologically nontrivial phases in symmetry class DIII. Therefore, we predict that Kramers pairs of Majorana zero modes will appear at the ends of Machida-Shibata chains, while two-dimensional lattices will host helical Majorana edge modes. Additionally, we discover extended regions in the Brillouin zone with vanishing superconducting pairings, which are lifted by the repulsive electron interactions. Our findings offer new perspectives for manipulating topological superconductivity and pairings in nonmagnetic adatom systems.