Higher-order topological superconductor on the bipartite triangular lattice

In order to investigate the possibility of construction of the higher-order topological superconductor on the triangular lattice, the different types of the coupling of chiral topological superconductor edge states are considered. It is demonstrated that the widespread criterion of the topological corner mode's appearance consisting in edge-state effective mass changing at the corner has to be modified in the case of multiple Dirac points in the edge-state spectrum. It is shown that the effective mass must be of the same sign at all Dirac points on one edge adjacent to the corner and be opposite at all the Dirac points on another one. For a two-dimensional system constructed from two chiral topological superconductors on the triangular lattice with inverted bands, two types of interactions leading to the higher-order topological superconducting phase are revealed.