High-${\mathit{T}}_{\mathit{c}}$ superconductivity of ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$/${\mathrm{PrBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ superlattices: An interlayer-coupling model

A simple model of intralayer and interlayer couplings based on a generalized BCS pairing theory of superlattices of layered superconductors is used to correlate the recently observed trends in the ${\mathit{T}}_{\mathit{c}}$’s of ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$/${\mathrm{PrBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ superlattices. These observed trends in the ${\mathit{T}}_{\mathit{c}}$’s are obtained in this model if certain inequalitities are satisfied among the direct and that mediated by the ${\mathrm{PrBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ intercell-interlayer, intracell-interlayer couplings. These inequalitities among the couplings may be reconciled in terms of the chemical structure of these systems.