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

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.

11 pages, 12 figures, to appear in Physical Review B (2011)

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• Low-energy electronic properties of Weyl semimetal quantum dot
• Single-Electron Transistor Made of a 3D Topological Insulator Nanoplate
• Phase diagram and phonon-induced backscattering in topological insulator nanowires
• Transport in Selectively Magnetically Doped Topological Insulator Wires
• Regular and irregular dynamics of Dirac-Weyl wavepackets in a mesoscopic quantum dot at the edge of topological insulator
• Transport in a thin topological insulator with potential and magnetic barriers
• Formation of bound states from the edge states of 2D topological insulator by macroscopic magnetic barriers
• Spectroscopy of van der Waals nanomaterials: Opportunities and Challenges
• Electronic confinement of surface states in a topological insulator nanowire