Magnetic field induced broadening of the resistive transition in epitaxial c-axis-oriented HgBa2CaCu2O6+δ films
Abstract
The resistive transition in epitaxial c-axis-oriented HgBa 2CaCu2O6+δ (Hg-1212) thin films (T c∼122K) in magnetic fields up to 9 T have been investigated. A considerably larger broadening of the resistive transition is observed for magnetic fields perpendicular to the ab plane than for fields parallel to the ab plane. Over the measured range of magnetic fields, the resistivity exponentially approaches zero as a function of decreasing temperature, suggesting a thermally activated flux creep behavior. The anisotropic characteristics of Hg-1212 are compared with other high-temperature cuprate superconductors and found to be less than for the Bi or Tl two-layer systems, but still considerably larger than for YBa2Cu3O 7-δ. This can be qualitatively explained on the basis of the differences in the insulator spacing layer thickness between the adjacent CuO2 layers in these cuprates.© 1995 American Institute of Physics.