Microwave Absorption Study on (Bi, Pb)-Sr-Ca-Cu-O Granular Superconductors

W. Jurga a, b, L. Piekara-Sady a and M. Gazda c a Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland b Department of Physics, A. Mickiewicz University, Poznań, Poland c Faculty of Applied Physics and Mathematics, University of Technology, Gdańsk, Poland

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Received: 6 11 2007;

(Bi, Pb)-Sr-Ca-Cu-O is considered as a system of 2201, 2212 and 2223 superconductors embedded in the insulating matrix. The size of the grains depends on the time of recrystallization. These types of ceramics exhibit a two-step transition to superconducting state. Because electrical properties depend among other on the Josephson coupling between grains, the magnetically modulated microwave absorption study was undertaken. Magnetically modulated microwave absorption signal was observed to arise just as temperature had been lowered below T1. The shape of this signal was studied to recognize the second temperature T2. Some strong oscillations appear on magnetically modulated microwave absorption at lower temperatures, which might be related to local percolation breakdown in superconducting network.

DOI: 10.12693/APhysPolA.114.253 PACS numbers: 74.70.-b, 74.72.-h, 74.45.+c