Ferromagnetic Semiconductor - Singlet (or Triplet) Superconductor - Ferromagnetic Semiconductor Systems as Possible Logic Circuits and Switches

摘要

We consider thin superconducting (S) films of thickness d $\ll \xi_{0}$,sandwiched between two ferromagnetic semiconducting insulators (FI) withdifferently orientated magnetizations - the FI-S-FI system. We calculate thedependence of the superconducting critical temperature on the orientation ofthe magnetization in the insulators and on the thickness of the superconductingfilm. The calculations are done for singlet as well as triplet superconductors.In the singlet case T_{c} depends on the relative orientation of the left andright magnetization only, while in the triplet case T_{c} depends on theabsolute orientation of magnetization. The latter property can serve as a kindof spin-spectroscopy of triplet and unconventional superconductors, forinstance in resolving the structure of the triplet order parameter in therecently discovered layered superconductor Sr_{2}RuO_{4}. The possibility oflogic circuits and switches, which are based on the FI-S-FI systems witharbitrary orientation of magnetizations in FI films, is analyzed too.