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

Abstract

We show here the existence of the indirect coupling of electron and magnetic or nuclear ion spins in self-assembled quantum dots mediated by electron-electron interactions. With a single localized spin placed in the center of the dot, only the spins of electrons occupying the zero angular momentum states couple directly to the localized spin. We show that when the electron-electron interactions are included, the electrons occupying finite angular momentum orbitals interact with the localized spin. This effective interaction is obtained using exact diagonalization of the microscopic Hamiltonian as a function of the number of electronic shells, shell spacing, and anisotropy of the electron-Mn exchange interaction. The effective interaction can be engineered to be either ferromagnetic or antiferromagnetic by tuning the parameters of the quantum dot.

Electron spin coherence near room temperature in magnetic quantum dots

“…The controlled incorporation of magnetic impurities in a semiconductor provides a means to manipulate magnetic and electronic interactions, one of the exciting challenges in modern condensed matter systems 1 . In particular, the interactions between magnetic ions and a host material constrained to low dimensionality provide an additional degree of freedom in tailoring physical properties and a route to the discovery of phenomena of fundamental and technological interest 2 3 4 5 6 .…”

Electronic and optical properties of diluted magnetic semiconductors quantum wells and quantum dots

“…This provides the emission theory for magnetically doped charged QDs. As a consequence, we observed that electron-electron interaction mediates indirect exchange interaction between electron and Mn and predict how to detect electron spin on half filled electronic shells [53,55].…”

“…Here we present a detailed description of the CI method. We use it to describe the electronic and optical properties of CdTe quantum dots doped with an single magnetic impurity [53,55,58,62,78]. To describe the QD electronic states, we model it as a two-dimensional harmonic oscillator.…”

“…For Mn-doped QD coupled to an electronic reservoir, it was shown theoretically that, depending on the rate J/T K , with J being the electron-Mn interaction and T K the Kondo temperature, it is possible to observe the underscreened Kondo state [54]. The emergence of an indirect electron-Mn interaction mediated by electron-electron interaction was also demonstrated [53,55]. Doping quasi-2D and -0D systems with magnetic impurities gives rise to new phenomena or the enhancement of certain effects that were already observed in nonmagnetic semiconductors.…”

“…The introduction of magnetic impurities in semiconductors quantum dots opens the possibility to investigating the physics of quasi-3D localized electrons interacting with localized spins [51]. Today, it is possible to manipulate the localized spin states by using light [42] or by adding electrons into the QD [52,53]. For Mn-doped QD coupled to an electronic reservoir, it was shown theoretically that, depending on the rate J/T K , with J being the electron-Mn interaction and T K the Kondo temperature, it is possible to observe the underscreened Kondo state [54].…”