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Finite-size effects in topological-insulator nanocylinders

Date: Thursday 16 March 2023 - 11:00
ONSITE: NEST meeting room
ONLINE: https://tinyurl.com/fabiotaddei
Speaker: Fabio Taddei (Istituto Nanoscienze-CNR and Scuola Normale Superiore)
Title: Finite-size effects in topological-insulator nanocylinders

Abstract: In this talk I present a theoretical study of nanowires made of a three-dimensional topological insulator (3DTI). Considering nanocylinders of finite radius R, either infinite or of finite height, finite-size effects are investigated in the energy spectrum and in the surface states. The latter are then used to calculate the dipole matrix elements for optical transitions with in-plane polarization. We find that the magnitude of the optical-transition matrix elements is strongly affected by the finite size of the nanowire.
Two approaches are developed: the first one is an exact numerical tight-binding model, while the second one, which allows us to obtain analytical results, is an approximated model based on a large-R expansion and on an effective boundary condition to account for the finite height of the nanocylinder. We find that the agreement between the two models, as far as eigenenergies and eigenfunctions are concerned, is excellent in a wide range of parameters values.

Host: Fabio Taddei, Stefan Heun

[Ultimo aggiornamento: 09/03/2023 13:56:42]