Vortex Behaviors Near Irreversibility Fields of a-Axis Oriented Y123 Films Inserted Pr123 Layers.

The irreversibility temperatures were measured for a-axis oriented and c-axis in-plane aligned Y123/Pr123 multilayer films in various magnetic fields. Pr123 layers act as two-dimensional (planer) c-axis correlated artificial pinning centers (APCs) in the multilayer films. In the irreversibility field -temperature (Birr T) curves, the crossover was observed near matching field Bφ, for the multilayer films, when the magnetic fields were applied parallel to the c-axis of the film (B//c). It is suggested the vortex state in Y123 films with two-dimensional APCs is Bose glass below the crossover field. The Birr T curves under B//a shifted toward lower temperature and magnetic field regions. [ABSTRACT FROM AUTHOR]