Temperature dependence of vortex flux pinning in grain-oriented YBa2Cu3O7

Magnetization measurements were made in grain-oriented YBa2Cu3O7 sample over the temperature range from 4.2 K up to Tc = 92 K. Within the applicability of Bean-critical state models, the saturated remnant magnetization (*DMR), as a detailed function of T, was used as measurable quantity of the average vortex flux pinning. Our results reveal that *DMr scales according to the empirical relations: *DMr (emu/cm3) = 168t7+26t1/2 along the c-axis, and *DMR (emu/cm3) = 45t9+13t1/2 along the a-b plane, where t = 1-T/Tc. For T/Tc < 0.3 the results show that the average pinning forces along the ab-plane are more influenced by temperature than along the c-axis. For T/ Tc > 0.3 the strength of the pinning forces is twice greater along the c-axis compared to pinning along the ab-plane, with same temperature dependence.