Electric transport and topological properties of binary heterostructures in topological insulators

Abstract

The design of devices with coupled hybrid structures offers an approach to creating synthetic topological materials. This work discusses the topological and transport properties of low-dimensional binary heterostructures of topological and trivial materials. By adjusting the parameters of each component, we control the global topological properties to enhance tunneling and optimize the transmission of the topological edge states (TES). Considering a one-dimensional tight-binding model, we build heterostructures of coupled chains employing Green’s functions (GF) formalism. We determine the topological characteristics of chains and couple them together, applying Dyson’s equation to generate the heterostructure. The intensity and decay length of the TES vary depending on the coupling parameters and the size of each chain. We investigate the topological diagrams phase using the energy bands of the periodic system and calculating the invariant from the Zak phase. Using cross-band condition, we derive analytical functions of the parameter space to get the phase topological diagram, which can be compared with the LDOS maps at zero energy. Finally, we calculate the differential conductance with the Keldysh GF technique to demonstrate the tunneling of the TES at the zero bias voltage and discuss potential design and experimental applications.