Delocalization of quasiparticles in quasi-two-dimensionaldisordered superconductors with s-wave pairing

We investigate localization behavior of quasiparticles indisordered multi-plane superconductors with s-wave pairing. Byintroducing disorder with random site energies, the spatialfluctuations of Bogoliubov-de Gennes pairing potential areself-consistently determined. The size dependence of rescaledlocalization length for a long bar is calculated by using thetransfer-matrix method. From the finite-size scaling analysis weshow that there exists a critical point of the disorder strengthW_c which separates the extended and localized quasiparticlestates in such quasi-two-dimensional systems. The associatedcritical behavior is studied and the relationship of the resultsto the number of planes is discussed.