Field-induced pinning in the vortex liquid phase of heavy-ion irradiated Bi 2Sr 2CaCu 2O 8 thin films and multilayers

Abstract

In-plane dissipation, R(H), in the vortex liquid phase is investigated in heavy-ion irradiated anisotropic Bi 2Sr 2CaCu 2O 8 epitaxial thin films and a highly anisotropic Bi 2Sr 2CaCu 2O 8/Bi 2Sr 2CuO 6 multilayer. In a well-defined region of the (H,T) phase diagram we observe a dip in the R(H) curves due to the pinning of vortices by the columnar defects created by irradiation. This decrease of dissipation is attributed to a field-driven confinement of vortices within the columnar defects. Our major conclusion from R(θ) curves is that the 2D angular scaling behaviour is valid in the entire (H,T) liquid region. These results indicate that in these systems the dissipation is always due to mobile 2D vortices, even in the presence of columnar defects.