Plasmon absorption of Au-in-CoAl₂O₄ linear nanopeapod chains

We investigated the plasmon absorption of Au-in-CoAl₂O₄ linear nanopeapod chains experimentally and theoretically. The Au-in-CoAl₂O₄ nanopeapods with uniform Au nanospheres (25–40 nm in radius) were synthesized by pulsed electrodeposition, followed by heat treatment, and the plasmon absorption peaks of the Au nanospheres (AuNS) embedded in CoAl₂O₄ red-shifted due to the size effect of the AuNS and the effect of the cladding dielectric medium. As a result of localized surface plasmon resonance, the plasmon absorption of the peapods can be modulated by tuning the size of the AuNS in CoAl₂O₄, and the experimental data are in good agreement with the calculated results based on Mie theory. In addition, we carried out the first-principles calculation based on the density functional theory with the LDA+U scheme to study the electronic structure and dielectric properties of CoAl₂O₄, and the theoretical results are consistent with the experimental data, which proves that LDA+U is a good approximation for CoAl₂O₄ or other spinels containing transition elements.