Geometry-Modulated Magnetoplasmonic Optical Activity of Au Nanorod-Based Nanostructures

Comprehension and modulation of optical activity at nanoscale have attracted tremendous interest in the past decades due to its potential application in many fields including chemical/biological sensing, artificial metamaterials, asymmetric catalysis, and so forth. As for the conventional molecular materials, magnetic field is among the most effective routes in inducing and manipulating their optical activity; whereas the magnetic optical activity at nanoscale calls for deeper understanding, especially for anisotropic noble metal nanoparticles. In this work, distinctly different magnetic circular dichroism (MCD) responses are demonstrated in gold nanorods (GNRs) with a derivative-shaped MCD signal corresponding to the transverse surface plasmon resonance (TSPR) band and a Gaussian-shaped signal at the position of the longitudinal surface plasmon resonance (LSPR) band. Furthermore, changing the aspect ratio of GNRs easily regulates such magnetoplasmonic CD response. More interestingly, GNR assemblies with ...