Evolution of the Magnetic and Optical Properties in CocoreAushell and (CoRh)(core) Au-shell Core-Shell Nanoparticles

Journal article, 2017

The magnetic and optical properties of CocoreAushell and (CoRh)(core)AU(shell) core-shell nanoparticles (14 shells, face centered cubic structure, 321 atoms) are investigated using spin-polarized density functional theory in the generalized gradient approximation. For CocoreAushell the properties show a clear dependence on the size of the Co core. For (CoRh)(core)Au-shell we vary the Co:Rh composition. We show that the distribution of the magnetic moments within the nanoparticle depends on strongly/weakly on the chemical environment for the Co/Rh atoms. The optical absorption shows sensitivity to both composition and chemical arrangement. In particular, (CoRh)(core)Au-shell nanoparticles show a blue shift for increasing Co concentration, whereas (RhCo)(core)Au-shell nanoparticles show a red shift for increasing Co concentration. The investigated nanoparticles uniquely couple the magnetism of the core to the optical properties of the Au shell and thus pave the way to optical tracking.