Studies on two-dimensional metallic photonic crystals and magnetic properties of patterned superconducting films

We studied the optical transmission and magneto-optical effect through a subwavelength hole array fabricated on a ferromagnetic cobalt Co thin film in comparison to a control unperforated Co film having the same thickness. We found that the perforated film sustains extraordinary transmission bands through the hole array, which can be well explained as due to light coupling to surface plasmons on the two film interfaces. We also found that due to resonant coupling to the surface plasmons, the magneto-optical Kerr effect in the spectral range of the anomalous transmission bands of the perforated Co film is much smaller than that in the control Co film.; We studied the magnetization behavior of patterned superconducting Pb and Nb films in the form of periodic hole arrays. Magnetization measurements were performed in a field cooled and in zero field cooled configurations. The patterned film magnetizations showed a very linear response to the cooling fields used. These superconducting hole arrays trap or lock in nearly all of the flux present at a higher temperature (T > TC) which was evident from their very small field cooled moments when compared to their zero field cooled moments. We propose a model based on the flux penetration idea to explain this linear behavior of the FCM Vs H slope per unit volume observed with the respective hole sizes. Further magnetization measurements performed as a function of the cooling rate supported our proposed model.; We also studied magnetization behavior of three-dimensional (3D) superconducting metallic opal structures. The opal structures were infiltrated with Pb and In filling all the voids in the structures. The observed small angle neutron scattering intensity pattern and the azimuthal scattering angle information extracted from these metallic opal structures showed that they possess a good structural quality and high metal-filling fractions.; The magnetization of these metallic opals showed a nearly complete trapping of the flux from high temperatures (T > TC), and the hysteresis measurements showed many jumps in magnetization at different constant temperatures arising from a closed and narrow network of superconducting metals occupying all the voids in the opal structure.