Energy spectrum and broken spin-surface locking in topological insulator quantum dots

Arijit Kundu, Alex Zazunov, Alfredo Levy Yeyati, Thierry Martin, and Reinhold Egger
Phys. Rev. B 83, 125429 – Published 30 March 2011

Abstract

We consider the energy spectrum and the spin-parity structure of the eigenstates for a quantum dot made of a strong topological insulator. Using the effective low-energy theory in a finite-length cylinder geometry, numerical calculations show that even at the lowest energy scales, the spin direction in a topologically protected surface mode is not locked to the surface. We find “zero-momentum” modes, and subgap states localized near the “caps” of the dot. Both the energy spectrum and the spin texture of the eigenstates are basically reproduced from an analytical surface Dirac fermion description. Our results are compared to microscopic calculations using a tight-binding model for a strong topological insulator in a finite-length nanowire geometry.

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  • Received 27 January 2011

DOI:https://doi.org/10.1103/PhysRevB.83.125429

©2011 American Physical Society

Authors & Affiliations

Arijit Kundu1, Alex Zazunov1, Alfredo Levy Yeyati2, Thierry Martin3,4, and Reinhold Egger1

  • 1Institut für Theoretische Physik, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
  • 2Departamento de Física Teórica de la Materia Condensada C-V, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
  • 3Centre de Physique Théorique, Campus de Luminy, case 907, F-13288 Marseille, France
  • 4Université de la Méditérannée, F-13288 Marseille, France

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Issue

Vol. 83, Iss. 12 — 15 March 2011

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