Magneto-transport and magnetization studies in BSCCO-2212 crystals

The transport and magnetization properties of layered Bi-based cuprate superconductors have been studied in detail. Kosterlitz-Thouless (KT) transition in this 2D system have been revealed in zero-field and the effect of magnetic field on this transition has been discussed. The melting transition and the irreversibility line (IL) have been determined and found to be very close to each other. A dimensional crossover from a 3D flux lattice (vortex glass state due to disorder) to a 2D vortex liquid state has been identified from our magnetization measurements at similar to 25 K. The detailed magnetic phase diagram has been discussed. The magneto-conductivity and magnetization measurements near T-c have been explained in the framework of fluctuation phenomena using 2D scaling theory. The wrong sign of hysteresis near T-c was found to be due to the manifestation of the fluctuation phenomena. The effect of heavy-ion irradiation on this material created effective pinning centres in the form of columnar tracks. The shift of IL to higher temperature, disappearance of double-peak anomaly, unidirectional pinning and reduced relaxation rate after irradiation have been discussed.