Finite-size effects in topological-insulator nanocylinders

  • NANO COLLOQUIA 2023 - first semester
Speaker
Fabio Taddei
Affiliation
CNR Nano
Date
2023-03-16
Time
11:00
Venue
ON SITE NEST meeting room – ONLINE https://tinyurl.com/fabiotaddei
Host
Stefan Heun
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.

Istituto Nanoscienze 

Consiglio Nazionale delle Ricerche

 

PEC: protocollo.nano@pec.cnr.it

Partita IVA 02118311006

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Istituto Nanoscienze Consiglio Nazionale delle Ricerche

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Pisa NEST

Piazza San Silvestro 12, I
56127 Pisa

phone +39 050 509525/418

fax +39 050 509550

Modena S3

via Campi 213/A, I 

41125 Modena 7

phone +39 059 2055629

fax +39 059 2055651″