Optical properties of charged quantum dots doped with a single magnetic impurity

Abstract

We present a microscopic theory of the optical properties of self-assembled quantum dots doped with a single magnetic manganese (Mn) impurity and containing a controlled number of electrons. The single-particle electron and heavy-hole electronic shells are described by two-dimensional harmonic oscillators. The electron-electron, electron-hole Coulomb as well as the short-range electron spin-Mn spin and hole spin-Mn spin contact exchange interactions are included. The electronic states of the photo-excited electron-hole-Mn complex and of the final electron-Mn complex are expanded in a finite number of configurations and the full interacting Hamiltonian is diagonalized numerically. The emission spectrum is predicted as a function of photon energy for a given number of electrons and different number of confined electronic quantum dot shells. We show how emission spectra allow to identify the number of electronic shells, the number of electrons populating these shells and, most importantly, their spin. We show that electrons not interacting directly with the spin of Mn ion do so via electron-electron interactions. This indirect interaction is a strong effect even when Mn impurity is away from the quantum dot center. arXiv:1309.0283v2 [cond-mat.mes-hall]

Electron-electron interaction mediated indirect coupling of electron and magnetic ion or nuclear spins in self-assembled quantum dots

“…In this case, the indirect e-Mn coupling gives rise to a fine structure of both initial and final states of the emission process. 18…”

“…There is currently interest in understanding the coupling of a localized spin, either magnetic impurity or nuclear spin, with spins of interacting electrons. 1,2 This includes the Kondo effect in metals [3][4][5][6][7] and quantum dots, [8][9][10][11] the impurity spin in diamond, 12,13 charged quantum dots with magnetic ions, [14][15][16][17][18] and nuclear spins coupled to fractional quantum Hall states. [19][20][21][22] Here we focus on a highly tunable system of quantum dots with a single magnetic ion and a controlled number of electrons.…”

“…14,23 Other studies focused on electron-electron interactions in excitonic complexes coupled with localized spins. 16,18,[23][24][25][26] Here we focus on the indirect coupling of electron and magnetic or nuclear ion spins in self-assembled quantum dots (QDs) mediated by the electron-electron interaction. With a localized spin placed in the center of the dot, only the spins of electrons occupying the zero angular momentum states of the s, d, .…”

Light-hole exciton mixing and dynamics in Mn-doped quantum dots

“…The coherent precession of a localized Mn spin embedded in a CdTe quantum dot has been recently probed [4] and the exciton luminescence of CdTe/ZnTe QDs in the presence of a cobalt ion was observed [3]. The formation of singlet and triplet states in self-assembled heavy-hole (HH) QDs in the presence of a Mn atom has been discussed recently [5,6]. The experimental studies of Léger et al [7] revealed that the in-plane QD asymmetry and Mn position competitively contribute to the level structure of the Mn "dressed" excitons and lead to very different photoluminescence spectra.…”

Exchange interaction-driven dynamic nuclear polarization in Mn-doped InGaAs/GaAs quantum dots

“…Semiconductor quantum dots (QDs) doped by a single or few magnetic impurities have been studied in the last decade in order to investigate the exchange interaction between spin carriers in the quantum regime [1][2][3][4][5][6][7][8][9] , and the potential of such system as a solid-state quantum bit [10][11][12][13][14][15][16][17][18][19] . In such QDs the dominant 2-spin interaction is the exchange interaction between the magnetic dopant and the QD-confined hole (up to a few meV).…”