Vortex pinning and J_c in high-T_c superconductors: advance form understanding toward some practical issues

摘要

IN teraction of vortex line lattice (VLL) in HTSC with crystal defects of various dimensionality dramatically affects quasi-static and dynamic behavior of vortices and J_c. Two kinds of ~quenched" VLL disorder are shown to contribute into anisotropic behavior of J_c and M_(irr) in HTSC single crystals: (i) random point-like defects-oxgen vacancies which serve as a weak but numerous pins, dominating by J_c (H, #theta# )-behavior on a background of strong collective vortex-vortex intefaction; (ii) extended defects (linear or planar), playing dramatic role in pinning if magnetic field is parallel (or inclined within a lock-in angle) to their direction. A dimensional crossover (DCO) 2D reversible 3D between states of VLL, having the disorder of different dimensionality, suggests to be responsible for anomalies in field and angular dependencies J_c, M_(irr) and F_p for perfect HTSC single crystals, i.e., for the "second peak of magnetization" -one of the most disputable feature of ovrtex matter.