Study of spin-switching by meansot superconductor-ferromagnet junction

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Ferromagnet(F)/Superconductor(S)/Ferromagnet(F) junction is theoretically expected to have different superconducting critical temperature(Tc) between parallel(P) and antiparallel(AP) coupling of the magnetic spins of both the ferromagnetic layers, that is huge change in electrical resistivity will be possible under the change in small magnetic field. This new junction is prospected to the practical use for the novel switching sensor having high S/N ratio under low driving magnetic field. In order to investigate the possibility above mentioned Tc-difference, we have done the Tc measurement in addition to the basic superconducting properties, which is necessary for the exploitation of new material, for the several multilayer systems, such as (1) S/N(normal metal), (2) S/F and (3) AF(antiferromagnet)/F/S/F. The results of the measurement for the systems (1) and (2) make clear the basic superconducting properties such as Tc and Hc2. Especially we have found the different oscillation behavior between S/F tri- and penta-layers reflecting the ο- and π- phases of superconducting pair funcfion. The result of the measurement for system (3) shows that, by means of selecting available size of F-layer's thickness, the magnetization measurement reveals the parallel and antiparallel coupling of both F-layers depending on the applied magnetic field. The difference in Tc accompanied by the parallel and antiparallel magnetic coupling, however, is very small even selecting optimum size of Slayer thickness.