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Bulk and interface quantum states of electrons in multi-layer heterostructures with topological materials.

Published version
Peer-reviewed

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Authors

Nikolic, Aleksandar 
Zhang, Kexin 
Barnes, CHW 

Abstract

In this article we describe the bulk and interface quantum states of electrons in multi-layer heterostructures in one dimension, consisting of topological insulators (TIs) and topologically trivial materials. We use and extend an effective four-band continuum Hamiltonian by introducing position dependence to the eight material parameters of the Hamiltonian. We are able to demonstrate complete conduction-valence band mixing in the interface states. We find evidence for topological features of bulk states of multi-layer TI heterostructures, as well as demonstrating both complete and incomplete conduction-valence band inversion at different bulk state energies. We show that the linear k z terms in the low-energy Hamiltonian, arising from overlap of p z orbitals between different atomic layers in the case of chalcogenides, control the amount of tunneling from TIs to trivial insulators. Finally, we show that the same linear k z terms in the low-energy Hamiltonian affect the material's ability to form the localised interface state, and we demonstrate that due to this effect the spin and probability density localisation in a thin film of Sb2Te3 is incomplete. We show that changing the parameter that controls the magnitude of the overlap of p z orbitals affects the transport characteristics of the topologically conducting states, with incomplete topological state localisation resulting in increased backscattering.

Description

Keywords

topological insulators, interface, position-dependent Schrodinger equation

Journal Title

Journal of Physics Condensed Matter

Conference Name

Journal ISSN

1361-648X
1361-648X

Volume Title

30

Publisher

IOP Publishing
Sponsorship
EPSRC (1208945)