Magneto-optical methods for magnetoplasmonics in noble metal nanostructures

The use of magneto-optical techniques to tune the plasmonic response of nanostructures-magnetoplasmonics-is a hot topic in active plasmonics, with fascinating implications for several plasmon-based applications and devices. In this exciting field, plasmonic nanomaterials with strong optical response to magnetic fields are desired, which is generally challenging to achieve with pure noble metals. To overcome this issue, several efforts have been carried out to design and tailor the magneto-optical response of metal nanostructures, mainly by combining plasmonic and magnetic materials or using ferromagnetic materials able to sustain a plasmonic response. However, despite their weak magneto-optical response, noble metals are a valuable model system allowing an accurate rationalization of magnetoplasmonic effects based on the interaction of magnetic fields with charge carriers. In addition, the emerging class of non-magnetic plasmonic heavily doped semiconductors is showing great potential for high performance magnetoplasmonics in the infrared range. In this Tutorial, the most common magneto-optical experimental methods employed to measure these effects are introduced, followed by a review of the major experimental observations that are discussed within the framework of an analytical model developed for the rationalization of magnetoplasmonic effects. Different materials are discussed, from noble metals to heavily doped semiconductors.