Confined electron states in two-dimensional HgTe in magnetic field: Quantum-dot versus quantum-ring behavior

Abstract

We investigate the electron states and optical absorption in square- and hexagonal-shaped two-dimensional (2D) HgTe quantum dots and quantum rings in the presence of a perpendicular magnetic field. The electronic structure is modeled by means of the $s{p}^3{d}^5{s}^{\ast }$ tight-binding method within the nearest-neighbor approximation. Both bulklike and edge states appear in the energy spectrum. The bulklike states in quantum rings exhibit Aharonov-Bohm oscillations in magnetic field, whereas no such oscillations are found in quantum dots, which is ascribed to the different topology of the two systems. When magnetic field varies, all the edge states in square quantum dots appear as quasibands composed of almost fully flat levels, whereas some edge states in quantum rings are found to oscillate with magnetic field. However, the edge states in hexagonal quantum dots are localized like in rings. The absorption spectra of all the structures consist of numerous absorption lines, which substantially overlap even for small line broadening. The absorption lines in the infrared are found to originate from transitions between edge states. It is shown that the magnetic field can be used to efficiently tune the optical absorption of HgTe 2D quantum dot and quantum ring systems.

arXiv comment21 pages, 8 figures, Published in Physical Review B

References in corpus (13)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Spectral and Fermi surface properties from Wannier interpolation
• Direct observation of the Aharonov-Casher phase
• Aharonov-Bohm oscillations in a mesoscopic ring with a quantum dot
• Two dimensional topological insulators with tunable band gaps: HgTe and HgSe monolayers
• Controllable Continuous evolution of electronic states in a single quantum ring
• Electro-absorption of silicene and bilayer graphene quantum dots
• Electric- and magnetic-field dependence of the electronic and optical properties of phosphorene quantum dots
• Aharonov-Bohm oscillations in p-type GaAs quantum rings
• Influence of quantum dot geometry on p-shell transitions in differently charged quantum dots
• Thin films of a three-dimensional topological insulator in a strong magnetic field: a microscopic study
• Helical edge states in silicene and germanene nanorings in perpendicular magnetic field