Synthesis and magnetic characterization of organically-capped gold nanoparticles

Gold nanoparticles (Au NPs) have been widely studied because of their novel optical, electrochemical, catalytic, biocompatible and excellent shelf store properties which play important roles in applications. The ferromagnetism, which may widen the potential applications in spintronics, magnetic and magneto-electronic devices, has been discovered in organically-protected Au NPs. Particle size and ligand capping effects are important in the induction of ferromagnetism. However, it is difficult to control these parameters independently by the traditional Brust method. Hence, a new two-step process has been developed to synthesize ferromagnetic Au NPs in this project to clarify the effects separately as complement of the traditional Brust method. To reveal the mechanism of ferromagnetic thiolate-capped Au NPs, various experimental methods and the density functional theory (DFT) calculations are applied. Furthermore, the fine surface morphology of Au adatom is experimentally observed and simulated by DFT calculations. They reveal the contribution of adatom in ferromagnetism and the details of electronic structure. In addition, the electronic transport properties, which are important in potential applications, are investigated after replacing thiol molecules by polythiolphene which is a well-known conductive polymer.