Role of Anisotropy in the Dissipative Behavior of High-Temperature Superconductors

In a comparative study of the dissipative behavior of various classes of high-Tc superconductors in large magnetic fields, we demonstrate that materials with a large electronic anisotropy, like the Bi and Tl compounds, have intrinsically smaller pinning energies than more isotropic materials. Consequently, the highly anisotropic materials exhibit thermally assisted dissipation down to temperatures far below Tc. In spite of small pinning energies, large critical current densities Jc can be observed in the critical-state regime at