Vortex molecule and i-soliton studies in multilayer cuprate superconductors

Abstract

We observed two dissipation peaks in the field cooled AC susceptibility measurements on aligned multilayered cuprate Superconductor, (Cu,C)Ba 2Ca2Cu3Oy[(Cu,C)-1223], and demonstrated that it is the direct experimental indication of the two-component vortex matter in the multilayered cuprates. We propose that, the second loss peak at lower temperature is due to the additional degree of freedom of the rotation of 'vortex molecule' composed of two fractional vortices, originated at two components, mediated by an i-soliton bond. To probe the dynamics of this vortex molecule, we measured frequency dependence of AC susceptibility response on aligned crystallites of (Cu,C)-1223 at different temperatures and DC fields. In second peak region, it gives resonance peak. The observed frequency dependence patterns of x"(T), for 0.5 T HDC, are rescaled with the resonating frequencies and show tail at low frequency region indicating that the dissipation is due to rotation and twisting of vortex molecule. The temperature dependence of the average relaxation time shows that the vortex molecule rotation/twisting glass state follow critical slowing down process. © 2008 IOP Publishing Ltd.