The similarities between thin sputtered films and high-Tc superconductive ceramics

Abstract

The system which will be considered in this paper is the thin film having, in a specific way, a modulated mass distribution along a given direction as consequence of the sputtering treatment. The theoretical analysis demonstrates that this system has some particular properties, which are very similar to the properties of the high temperature superconductive ceramics. Therefore, taking into account their layered structure, we propose to consider the sputtered high temperature ceramic as a system of thin sputtered film-blocks. The blocks, depending on the film thickness as well as on the results of the sputtering treatment, could exhibit (SP-blocks) or not exhibit (N-blocks) superconductive properties. Here, the word "superconductive" has a particular meaning, because the superconductive state is in fact the normal state with no phonons, as well with no Cooper pairs. Namely, due to the freezing of the low energy acoustical modes which arises in the SP-blocks, the current in these blocks could be considered as a superconductive one because the carriers propagate in the media with no phonons. The above mentioned model assumptions lead to results which give possible explanations for the following particular properties of high Tc ceramics: the great carrier effective mass, the small value of the Fermi level, the anisotropy of the superconductive properties, the strong pressure dependence of Tc, the increasing of Tc with the increasing of the number of layers in the elementary cell, the existence of the specific heat jump and the dependence of the superconductive properties on the stoichiometric proportions x and δ. © 1989.