Sublattice-sensitive Majorana modes

Abstract

For two- and three-dimensional topological insulators whose unit cells consist of multiple sublattices, the boundary terminating at which type of sublattice can affect the time-reversal invariant momentum at which the Dirac points of helical boundary states are located. By incorporating a generic theory and a representative model, we reveal that this interesting property allows the realization of Majorana modes at sublattice domain walls forming on the boundary when the boundary Dirac points of the topological insulator are gapped by appropriate superconductivity in proximity. Remarkably, we find that the sensitive sublattice dependence of the Majorana modes allows their positions to be precisely manipulated by locally controlling the terminating sublattices or boundary potential. Our work reveals that the sublattice degrees of freedom commonly found in materials open a different route to realize and manipulate Majorana modes.