Far- and near-field broad-band magneto-optical functionalities using magnetoplasmonic nanorods

We have performed a systematic study of magnetoplasmonic Au/Co/Au nanorods with different long/short axes ratio arranged in a disordered fashion but with the same spatial orientation of their axes. We show that the magneto-optical response can be tuned from the visible to the near-infrared range by changing the long/short axes ratio. Moreover, the analysis of the magnetic field induced polarization conversion indicates a different behavior for the far field and for the near field. In particular, the far-field polarization conversion of the nanorod does not depend on the incident polarization, whereas the near field does. This anticipates direct consequences for near-field interactions, since the interacting elements at different spatial positions could give rise to different magneto-optical responses.Funding from the Spanish Ministry of Economy and Competitiveness through grant AMES MAT2014-58860-P is acknowledged. N.d.S. is thankful for the financial support from Spanish Ministerio de Economía y Competitividad (MINECO) project FIS2015-69295-C3-3-P.Peer reviewe