REFLECTIVITY OSCILLATIONS IN SUPERCONDUCTING SUPERLATTICES NB SIO2/

The reflectivity of superconducting superlattices Nb / SiO2 was experi mentally studied at room temperature in a spectral range 450-5000 cm(- 1). It was found that the reflectivity as a function of SiO2 layer thi ckness oscillates with a period 3.5 Angstrom. This value coincides wit h the period of oscillations of the superconducting transition tempera ture found earlier on these superlattices. We suppose that in both cas es the oscillations are due to changes of electron state density. So i t is possible to considerably influence the superconducting transition temperature of a superconducting film by making sandwich-like structu res using thin dielectric layers. (C) 1995 Academic Press Limited