ANOMALOUS ANGULAR-DEPENDENCE OF DISSIPATION IN LAYERED HIGH-TEMPERATURE SUPERCONDUCTORS

Resistive behavior of Bi2Sr2CaCu2O8+y and YBa2Cu3O7-y in their mixed state has been investigated as a function of magnetic field angle, strength, transport current density and temperature. Striking novel features in the angular dependence of resistivity have been found at elevated transport current densities. In the case of YBa2Cu3O7-y, an anomalous enhancement of dissipation occurs in an angular range, 5-degrees < theta < 30-degrees (theta being the field angle relative to the ab-plane). This is compared with a similar phenomenon we reported earlier for Bi2Sr2CaCu2O8+y which occurs in a much lower angle range, 0.1-degrees < theta < 0.5-degrees. Possible origins of such anomalous angular dependences of dissipation are discussed in the context of flux structure and dynamics in layered high-temperature superconductors under tilted magnetic fields.