Topological superconductivity in a two-dimensional Weyl SSH model

Abstract

We study the emergence of topological superconductivity in a two-dimensional Weyl system, composed of stacked Su-Schrieffer-Heeger (SSH) chains. A previous analysis of the model showed that the addition of an attractive Hubbard interaction between spinful electrons leads to a superconducting state that has an intricate pairing structure, but is topologically trivial. Here we consider a pairing interaction that couples spinless fermions on opposite sublattices within the same unit cell. We observe that this physically motivated, momentum-independent pairing interaction induces a topological superconducting state, characterized by a gap function with a nontrivial phase, as well as Majorana and Fermi arc edge states along the edge perpendicular to the direction of the SSH dimerization. In addition, we observe a transition as a function of pairing interaction strength and chemical potential, indicated by a change in the sign of the topological charge carried by each of the four Bogoliubov-Weyl nodes.