Band Structure with Möbius Topology in a Heterostructure of Topological Insulators

An effective model of a heterostructure consisting of alternating layers of two-dimensional topological and normal insulators with nonsymmorphic projective symmetry has been proposed. The band structure of this system has been shown to have a Möbius topology in both the gapped and gapless phases, leading to the formation of protected Dirac points. A non-Hermitian generalization of the Hamiltonian that preserves the nonsymmorphic symmetry and leads to a topologically protected non-Hermitian skin effect has been proposed.