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Free keywords:
high-T-c superconductors; irreversibility line; flux creep
Abstract:
A variety of Hg-1223 high-T-c superconducting: systems, partly substituted by lead or fluorine, are investigated by means of magnetic susceptibility measurements. As already observed earlier, the double peak structure in the imaginary parts of the ac signals below about 1 T is confirmed indicating different pinning mechanisms. Irreversibility lines are determined from the upper peak values and analysed applying the theory of Matsushita which is based on a depinning mechanism caused by thermally activated flux creep. It leads to a suitable description in the whole temperature range investigated and allows a discussion of differences of the various samples. (C) 2002 Elsevier Science B.V. All rights reserved.
