Critical current anisotropy in high-Tcsuperconductors

Using grain-aligned samples, we have investigated the anisotropy of the superconducting critical current in three different copper oxide superconductors. At low temperatures there are large anisotropy differences between the materials, but at higher temperatures we find that the anisotropy is both small and roughly material independent. This result suggests that a small intrinsic critical current anisotropy may exist in high-$T_c$ superconductors.