High Tc Superconductors for Plasmonics and Metamaterials Fabrication: a Preliminary Normal State Optical Characterisation of Nd123 and Gd1212

Metamaterials and plasmonic structures applications are strongly limited, in the high frequencies by dissipative losses in structures, due to the low conductivity of most used metals in this frequency range. High temperature superconductors (HTSC) are plasmonic materials at nonzero temperature and they can provide a possible approach to solve this problem. HTSC have zero or even negative dielectric constant and present two kind of charge carriers (electrons or holes), characteristics that are further very attractive for plasmonic applications. For this reason a detailed study of the high frequency response of these materials can be interesting in order to correctly investigate HTSC optical parameters. In this paper we report the Fourier Transform Infrared Spectroscopy (FTIR) and some ellipsometric measurements made on NdBa2Cu3O7-? (Nd123) sample and on ruthenocuprate superconductor GdSr2RuCu2O8-? (Gd1212) in visible and near infrared regime. Nd123 presents, indeed, the highest Tc (96K) and the most interesting magnetic response properties among YBCO-like cuprate superconductors, whereas the coexistence in the same cell of superconductivity and magnetic order below Tc in Gd1212 can be an interesting feature in the metamaterials field. The obtained results confirm the promising features of the considered materials.