Direct observation of electronic anisotropy in single-crystal Y1Ba2Cu3O7-x

We report direct observation of the anisotropic electronic behavior of the high-temperature superconductor Y1Ba2Cu3O7-x. Critical-field and critical-current measurements performed on single crystals show anisotropies of 10 and greater. Critical supercurrent densities in favorable directions in single crystals are 3×106 A/cm2 in low fields at 4.5 K and remain above 106 A/cm2 to beyond 40 kG. © 1987 The American Physical Society.