Fig. 1 Magneto-optical plasmonic material. (a) Structure, (b) periodically-arranged Au particles, (b) randomly-arranged Au particles.

An interaction between a magnetic material and light are called as magneto-optical effect. Propagated polarized light in a magnetic material is rotated to left or right direction, which is decided by direction of magnetization. This phenomena is called as Faraday effect. Even if a thin film, to obtain large Faraday rotation angle, we investigates composite materials with Au particles and magnetic garnet film by utilizing localized surface plasmon resonance. Figure 1 (a) shows a schematic structure of the composite film, which includes Au particles with (b) periodically arranged Au particles and (c) randomly arranged Au ones. In the study, we investigate to decide wavelength of plasmon resonance and magnitude of enhanced rotation angle. Experiments and FDTD calculations are used to understand the optical and magneto-optical properties.

Fig. 2 (a) Near-field optical microscope. (b) Topograph image and (c) simultaneously obtained optical one for a periodic columnar structure.

We developed advanced measurement systems to obtain necessary data and also fabrication systems to prepare samples. These are a scanning tunneling microscope (STM) for observation of atoms on surface, an atomic force microscope (AFM) for observation of surface structure with sub-micrometer range, a magnetic force microscope (MFM) for obtaining magnetic structure on surface, a scanning near-field microscope (SNOM) for observation of optical images with a sub-wavelength scale, which were developed as collaboration with companies. Furthermore, we developed a laser lithography system for patterning with a micro-meter scale, a polarization measurement system for obtaining polarization states including magneto-optical effects. At present, an observation method inside a material is developed.