Abstract: | Colloidal nanostructures are known for their tunable optical properties by variation of size, shape, and composition, while magnetically doped nanostructures endow them with an additional degree of freedom. The confined structures enhance interaction between photo-generated carriers (electron and hole) and spins of the magnetic impurities, hence, encouraging unique properties, like giant magnetization and giant g-factor of the carriers. The degree of magnetization depends on the shape, size, type of impurity, and position concerning the host-carrier distribution function. The carrier-impurity interaction was mainly investigated using an optically detected magnetic resonance (ODMR) spectroscopy. An ODMR spectrum refers to a plot of a change in luminescence intensity due to a magnetic resonance perturbation at the excited state. Modulation dependence ODMR can revile the spin dynamics in the NCs. Theoretical model, using spin Hamiltonian containing Zeeman interaction, carrier-impurity spin-exchange, and electron-hole exchange interactions, assisted in simulating the ODMR spectrum. The first and second projects focused on the magneto-optical properties of Mn+2 ions embedded in CdSe/CdS nanoplatelets (NPLs) and nanorods (NRs), positioning a single or a few Mn+2 ions in the shell regime. The pristine CdSe/CdS structures mainly show a quasi-type-II band-edge energy alignment between the core and the shell constituents, allowing electron distribution over the entire structure. So, selective positioning of magnetic impurities in the shell regime permits selective monitoring of the electron-Mn+2 spin-exchange interaction. The experimental results showed a major band, with a sextet split fine structure between the NPLs and a two-band with a different character in the NRs. The third project included the study of the Cu@CdSe/CdS and CuInS2/(CdS) CQDs. The study focuses on open questions related to the oxidation state of the copper ions, identification of their local sites and on the influence of the surrounding on the radiative and spin relaxation times. The fourth project investigates Ni2+ ions doping into cesium lead halide perovskite with a chemical formula CsPb(Br1-xClx)3. The study revealed spin-flip processes of both electron and hole with g-phenomenological factors deviating from the electronic band-edge, indicating their localization or shallow trapping at halide or metal vacancies. Moreover, the study provided rich information about the recombination processes. The discussed materials are of particular interest for various future applications such as electro-luminescent display, photovoltaic cells, and spin-based technologies.
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https://technion.zoom.us/j/91692396649?pwd=MURDdkxkWEV5bzA2MENWOXFlQ2ZEUT09.
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