SchiroMag - Research project

The thesis is based on the exploitation of magnetic metasurfaces, which represent today an important and novel branch of research activity in view of the possibility to control their optical response with an external magnetic field. On the other hand, a certain type of metasurfaces is of
particular interest for applications – chiral metasurfaces, which react differently to left- and righthanded circularly polarized waves (chiroptical response). One of their applications is the realization of biosensors in order to easily distinguish the enantiomers of chiral molecules. Since the chiroptical response of natural chiral objects is weak, chiro-magnetic metasurfaces will provide an additional degree of freedom for the exaltation of this response. The thesis will be devoted to the exploitation
of chiro-magnetic metasurfaces with micro- and/or nano-patterns. The objective is to obtain a large magneto-optical response, particularly in the case where the chiral geometry of these patterns allows to combine the magneto-optical and chiro-optical responses of the structure. The magneto-optical effect then allows to modulate the chiral response around an operating point, and thus enhance the sensitivity of the device. The magnetic layers will be made of a nanocomposite consisting of
magnetic nanoparticles of cobalt ferrite CoFe2O4 dispersed in a silica matrix. Since the magnetic relaxation frequency of the nanoparticles is high (in the GHz domain), this will open up the field of applications for the control of the optical responses of metasurfaces (beam-steering, spatial light modulators, etc.) with a magnetic field.