Composition dependence of magneto-optical response in Ag/Co dimer nanodot arrays

In this work, we fabricated ordered Ag/Co dimer nanodot arrays by using anodic aluminum oxide (AAO) templates combined with magnetron sputtering. First of all, we studied the optical properties of the nanodot arrays with different Ag/Co ratios while keeping the total thickness constant. The sharp absorption peaks were found in visible spectral range due to the excitation of localized surface plasmon resonances (LSPR) of Ag/Co nanodot arrays, and the absorption peak decreases and slightly blue shifts with the decreasing of Ag ratio. Further, we explored the magneto-optical (MO) properties of nanodot arrays, and found that the excitation of LSPR induces electromagnetic (EM) enhancement near the surface of the Co, which exhibits a sizable MO activity.