Influence of direct and alternating transport current on the diamagnetic response of Bi-based ceramics

Abstract

AC susceptibility measurements performed on single-phase ceramic Bi2Sr2Ca2Cu3Oy slab carrying direct Idc or alternating Iac transport current are presented. A strong suppression of intra- and intergranular superconducting properties by transport current was observed. It is displayed as a sharp shift of real χ′ and imaginary χ″ components of ac susceptibility to lower temperatures with increasing I. The hysteretic losses peak shifts to low temperatures as transport current density j increases at the rate Δtδj ≈ 4 K/(A/cm2). The increase of I, in the contrary to increase of exciting magnetic field Hac, does not broaden the χ′(T) and χ″(T) curves. The influence of ac transport current is quite different from that of dc current. With increasing Iac the value of both the in-phase and quadrature components of diamagnetic response increases, while increase of Idc does not effect the value of χ′(T) and χ″(t).