Electric field tuning spin splitting in topological insulator quantum dots doped with a single magnetic ion

TL;DR

This paper theoretically demonstrates how electric fields and magnetic ion positioning can control spin splitting and optical properties in topological insulator quantum dots, paving the way for advanced topological electro-optical devices.

Contribution

It reveals the tunability of spin states and optical transitions in HgTe topological insulator quantum dots doped with a single magnetic ion, highlighting new control mechanisms.

Findings

Magnetic ion position significantly affects energy spectrum and electron density.

Electric fields modulate spin splittings via exchange interaction.

Observed bright-to-dark transitions and anti-crossing in PL spectra.

Abstract

We investigate theoretically the electron spin states in disk-shaped HgTe topological insulator quantum dots (TIQDs) containing a single magnetic $Mn^{2+}$ ion. We show that the energy spectrum and the electron density distribution of the topological edge states in HgTe TIQD can be modulated significantly by the position of the magnetic $Mn^{2+}$ ion. The numerical results further demonstrate that the electric fields not only tune the spin splittings of edge states via the $\emph{sp-d}$ exchange interaction between the electron (hole) and the magnetic $Mn^{2+}$ ion but also give rise to the bright-to-dark transitions and anti-crossing behaviors in the photoluminescence (PL) spectra. Such spin properties of HgTe TIQDs with single $Mn^{2+}$ ion as illustrated in this work could offer a new platform for topological electro-optical devices.