Vortex lattice dynamics in DyBa2Cu3O7/(Sr1−xCax)RuO3 multilayers

Abstract

We have investigated vortex dynamics in ${\mathrm{DyBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$/(${\mathrm{Sr}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Ca}}_{\mathit{x}}$)${\mathrm{RuO}}_3$ multilayers in parallel and perpendicular applied magnetic fields. In both configurations, we have measured activation energies U for flux motion and determined vortex coupling through either ferromagnetic (${\mathrm{SrRuO}}_3$) or nonmagnetic (${\mathrm{CaRuO}}_3$) barriers. Coupled motion of pancake vortices belonging to different ${\mathrm{DyBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ layers occurs for nonmagnetic barriers (${\mathrm{CaRuO}}_3$) as large as several hundreds of Å . In the case of ferromagnetic barriers (${\mathrm{SrRuO}}_3$), 50 Å was found to be sufficient to decouple the vortices between the barrier. The ferromagnetism present in the ${\mathrm{SrRuO}}_3$ barrier is believed to be responsible for such behavior. © 1996 The American Physical Society.