Normal-state re-entrant peak in the vortex transformer measurement for Bi-2212/Bi-2223 intergrowth single crystals

A normal-state re-entrant behaviour in the Bi2Sr2CaCu2O8/Bi2Sr2Ca2Cu3O10 (Bi-2212/Bi-2223) intergrowth single crystals is observed with the 'flux-transformer' measurements. After entering the superconducting state at Tc1=107 K, the intergrowth system re-enters the normal state at a temperature slightly higher than the superconducting transition temperature of the Bi-2212 phase (Tc2=92 K). This re-entrant phenomenon is consistent with our previous observations in the measurements with the conventional four-probe technique. However, some new behaviours have been found in the flux-transformer measurements, namely a two-head peak near Tc2 is observed. The position and the height of the peak are sensitive to driving currents and applied magnetic fields. The origin of the two-head peak has been attributed to the vortex motion and the superconducting transition of the Bi-2212 matrix