Design Synthesis for Magnetic Impurity Positioning within CdSe/CdS Core/Shell Colloidal Quantum Dots

Recently, research interest has shifted toward colloidal quantum dots (CQDS) embedded with magnetic impurities, such as a Mn²⁺ ion [1]. The incorporation of magnetic ions initiates spin exchange interaction between the guest ions’ spins and host carriers’ spins, the so called sp-d exchange interaction, which induces mutual spin alignment followed by creation of giant magnetization and a long spin-coherent time [2]. Hence, present of magnetic impurities strongly influence the optical, electronic and magnetic properties of the semiconductors.

Here, we will present a design of colloidal synthesis procedure for incorporation of Mn²⁺ ions into CdSe/CdS core/shell CQDs by controlled layer-by-layer growth methods. Such a procedure allows us to positioning of the Mn ²⁺ ions at a desired radial distance from the nanocrystal (NC) centre, either within the core or within the shell. Special platform of NCs will permit selective interaction of the resident host carriers with the guest ion`s spins. We show evidence of successful in embedded Mn²⁺ ions at low dilution in CdSe/CdS CQDs and the electron spin resonance (ESR) studies reveal the Mn²⁺ ions local environments within the QDs

[1] Beaulac, R.; Archer, P. I.; Ochsenbein, S. T.; Gamelin, D. R. Mn2+-Doped CdSe Quantum Dots: New Inorganic Materials for Spin-Electronics and Spin-Photonics. Advanced Functional Materials, 2008, 18 (24), 3873-3891.

[2] Govorov, A.O.; Kalameitsev, A.V. Optical properties of a semiconductor quantum dot with a single magnetic impurity: photoinduced spin orientation. Phys. Rev. B. 2005, 71(3), 35338.