Synthesis and Characterization of Transition Metal Doped CdSe Dilute Magnetic Nanostructures

Abstract

Spintronics represent field of electronics, in which the spin of electron is exploited along with its charge. DMS materials are promising for future spintronic device applications. A lot of research has been devoted to generate magnetism in semiconductor materials via doping of transition metals, known as DMS materials. However, origin of magnetism remains still debatable till date. Also, from the application point of view, low Curie temperature (TC) further hinders their practical utility, and thus, many efforts have been made to find ferromagnetic DMS having TC higher than room temperature. This has motivated us to carry out investigations in order to achieve ferromagnetism at room temperature and understand its origin, as well. In the present thesis work, synthesis of pure CdSe and Fe, Ni, and Co-doped CdSe nanostructures (nanoparticles and nanorods) have been carried out by chemical route. Their structural, morphological, elemental, optical and magnetic properties have been studied using various characterization techniques such as XRD, Raman spectroscopy, TEM, EDS, PL, UV-visible, ESR and VSM/SQUID. The observations and their possible origins have been discussed in detail. Magnetic study revealed presence of room temperature ferromagnetism in both pure and doped CdSe nanostructures. However, observation of weak ferromagnetism in CdSe nanostructures is ascribed to defects and small particle size. Nature of dopant and its concentration both have been found to play a crucial role in deciding the overall magnetic behavior of the system and is attributed to exchange interactions between dopant ions.