Magnetic Modulation of Surface Plasmon Resonance by Tailoring Magnetically Responsive Metallic Block in Multisegment Nanorods

The modulation of quasi-one-dimensional plasmonic nanorods via the utilization of localized surface plasmon resonance is critical for achieving local dynamic tuning on the nanoscale as well as for fundamental studies. In particular, a magnetic field has been used as an effective external stimulus that can be activated in an instant and reversible way. However, limited synthetic procedures hinder the full-utilization of one-dimensional nanorods, making it challenging to tailor magnetic-responsive plasmonic materials. Here, we report the magnetic manipulation of Au nanorods with ferromagnetic Ni segments, which facilitate orientational control, allowing for the selective tuning of surface plasmon resonance. Ni segments served as a magnetic responder for the external magnetic field for guided-alignment as well as bridges to mediate intrasurface plasmon coupling of nanorods. We investigated the correlation between the optical properties and the aspect ratio of Ni segments. By designing various configurations in ferromagnetic segments, magnetic cancellation and enhancement in optical performance were demonstrated. This simple but straightforward configuration will expand the understanding of plasmonic nanorods, furthering the accessibility of multiblock nanorods.