Maximum Pinning Energy of Vortices in Anisotropic and Layered Superconductors

In type-II superconductors the pinning force which determines the critical current density J c , and the pinning energy U which determines thermally activated depinning, in principle are different quantities. Long pinning channels generated by high-energy heavy-ion irradiation, in YBCO can enhance both J c and U , but in the strongly layered BSCCO they may enhance J c without enhancing U , since the pancake vortices in the layers depin individually. This is the reason why in BSCCO flux creep is large down to rather low temperatures.