CRITICAL-CURRENT DENSITY OF 4-CUO2-LAYER TLBA2CA3CU4O11-CRYSTALS(DELTA SINGLE)

A key requirement for technological application is to have superconduc tors with high critical current density at practical operating tempera tures and magnetic fields. The critical current density is strongly re lated to underlying properties of high T-c superconductors, such as la ying, anisotropy and other intrinsic material structures. The thallium -based superconductors attracted much attention at an early stage main ly due to their high superconducting transitions. Our single crystal s tudies on TlBa2Ca3Cu4O11+delta show that these materials appear to be a better choice for achieving higher critical current density because of a stronger interlayer coupling between superconducting layers.