Electromagnetic properties of a nearly ferroelectric superconductor in layered structure

Electromagnetic microwave properties of a superconducting bilayer structure made of a high-temperature superconductor (HTSC) and a nearly ferroelectric superconductor (NFE SC) are investigated. Microwave properties are analyzed by the effective surface impedance calculated by using the impedance transform method. It is found that the anomalous resonant peaks in the surface resistance appearing in an NFE SC slab are greatly affected by the presence of the HTSC film. In the case where the HTSC is in front of the NFE SC, the resonant peaks are shifted to higher frequencies and the peak heights are strongly suppressed as well. However, if the HTSC is at the backside of the NFE SC, the peak heights are strongly enhanced in addition to shifting to higher frequencies.