Second and third peaks in the non-resonant microwave absorption spectra of superconducting Bi2212 crystals

Abstract

Non-resonant microwave absorption (NMA) measurements at liquid nitrogen temperature with systematic microwave power variation showed a two-peak structure in the Bi-2212 textured crystals, similar to that observed in the Bi-2212 single crystals (Srinivasu, et al., in J. Supercond. Incorp. Nov. Magn. 14:41, 2001). NMA signals from the aged Bi-2212 single crystals show an emergence of a ‘third peak’ as a function of microwave power. The authors qualitatively interpret these second and third peaks as due to the microwave power induced phase locking of several number of junctions into coherent groups and then the destruction of the phase locking by the applied DC field leading to decoupling or fluxon motion, which gives the loss in individual junctions belonging to these otherwise coherent groups.