Columnar-defect-induced resistivity minima and Bose glass scaling of linear dissipation in Tl₂Ba₂CaCu₂O₈ epitaxial films

Abstract

The angular dependence of the flux flow resistivity ρ(θ,T,H) in Tl₂Ba₂CaCu₂O₈ is measured as the external field is brought into alignment with heavy-ion-irradiation-induced columnar defects. A flux lock-in state, manifested as a minimum in the ρ(θ,T,H) data, evolves as the system is cooled deeper into the mixed state. This observation provides compelling evidence for non-zero line tension of vortices in this highly anisotropic superconductor. The temperature dependence of the flux flow resistivity at perfect alignment is consistent with Bose glass theory of vortex localization at columnar defects.