Magnetic anisotropy of singly Mn-doped InAs/GaAs quantum dots

TL;DR

This study investigates the magnetic anisotropy in singly Mn-doped InAs/GaAs quantum dots using micro-photoluminescence spectroscopy, revealing unique spectral splitting behaviors influenced by magnetic field orientation and complex spin interactions.

Contribution

It introduces a theoretical model that accounts for local strain and anisotropic exchange interactions, explaining the observed magnetic anisotropy effects in Mn-doped quantum dots.

Findings

Spectral splitting of positive trion (X+) into circularly polarized components in magnetic fields.

Transverse Zeeman splitting of the neutral acceptor complex A0 explains the spectral features.

Theoretical model aligns well with experimental observations, highlighting strain and exchange effects.

Abstract

We report on the micro-photoluminescence spectroscopy of InAs/GaAs quantum dots (QD) doped by a single Mn atom in a magnetic field either longitudinal or perpendicular to the optical axis. In both cases the spectral features of positive trion (X+) are found to split into strongly circularly polarized components, an effect very surprising in a perpendicular magnetic field. The field-induced splitting is ascribed to the transverse Zeeman splitting of the neutral acceptor complex A0 issued by the Mn impurity, whereas the circular optical selection rules result from the p-d exchange which acts as a very strong longitudinal magnetic field inhibiting the spin mixing by the transverse field of the QD heavy-hole ground state. A theoretical model of the spin interactions which includes (i) the local strain anisotropy experienced by the acceptor level and (ii) the anisotropic exchange due to the out-of-center Mn position provides a very good agreement with our observations.