Tuning the Composition of Alloy Nanoparticles Through Laser Mixing: The Role of Surface Plasmon Resonance

In this work we report a technique for the preparation of AuxNi1-x alloy nanoparticles based on pulsed laser irradiation in liquid of Au and Ni@NiO colloidal mixtures. The structural and compositional characterization of the obtained materials, performed through X-ray diffraction and transmission electron microscopy coupled with energy dispersive X-ray spectroscopy, has shown a correlation between the final alloy composition and the different Au to Ni@NiO ratio in the irradiated mixture. With the support of theoretical calculations, we propose as possible mechanism for the formation of the alloy structures a temperature increase, enhanced by the strong absorption of gold surface plasmon resonance at resonant wavelength, and a subsequent melting of the structures. Optical characterization through UV-vis spectroscopy and magnetic characterization through SQUID magnetometry confirm a coexistence of the plasmonic and magnetic behaviors in the hybrid systems. In view of such results, AuxNi1-x alloy nanoparticles could be a promising base material for devices requiring both plasmonic and magnetic properties.