Topological transitions in a model for proximity-induced superconductivity

Recent advancement in the theoretical understanding of triplet superconductivity has lead the researchers to believe in the technologically promising nature of p-wave superconductors. These superconductors have become a natural platform to look for non-abelian Majorana zero modes which can, in principle, be used to develop decoherence-free quantum computers. Although Strontium Ruthenate Sr2RuO4 and some Uranium based materials like UTe2 are possible candidates for a p-wave superconductor, a formal discovery of a p-wave superconductor awaits. Using a prototype model for proximity-induced superconductivity on a bilayer square lattice, we show that interlayer tunneling can drive change in topology of the Bogoliubov quasiparticle bands. Starting with topologically trivial superconductors, transitions to a nontrivial px+i py state and back to another trivial state are discovered. We characterize these phases in terms of edge-state spectra and Chern indices. We show that these transitions can also be controlled by experimentally viable control parameters, the bandwidth of the metallic layer, and the gate potential. Insights from our results on a simple model for proximity-induced superconductivity may open up a new route to discover topological superconductors.