AC magnetic susceptibility of Bi2223-system

Abstract

The AC magnetic susceptibilities χ AC of a Bi2223 sintered sample were measured by the Hartshorn bridge method. The linear AC χ′ 0 showed the two-steps behavior at T C1 and T C2 , where T C1 > T C2 . The χ′ 0-data between T C1 and T C2 has no H AC -dependence and agreed well with those of powder specimen, and they can be regarded as the intragrain magnetic susceptibility. Below the inter-grain transition temperature T C2 the χ″ 0 showed a positive peak. The temperature dependence of χ′ 0 and χ″ 0 were analyzed by the Bean's critical-state model. As a result, the temperature dependence of critical current density J C ∝ (1 − T/T C2) β was obtained with β = 2.3–2.6. The non-linear χ′ 2 and χ″ 2 below T C2 resemble the behaviors derived from the Bean model, but the negative divergence of χ′ 2 may show the evidence of d-wave paring in the present Bi2223-system.