Physics Journal of the Indonesian Physical Society
VORTEX SOLID AND VORTEX LIQUID CHARACTERISTICS OF AN EXCESSIVELY DOPED BI2SR2CACU2O8+\DELTA SINGLE CRYSTAL
Darminto1 and M.O. Tjia2
1Department of Physics, Faculty of Mathematics and Science, Sepuluh Nopember Institute of Technology, Sukolilo, Surabaya 60111, Indonesia
2Department of Physics, Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40132, Indonesia
The enhanced disorder and reduced anisotropy of vortex system induced by excessive oxygen doping are shown to have remarkable effects on the vortex characteristics in both its solid and liquid phases of a single crystalline Bi2Sr2CaCu2O8+\delta. A conspicuous full valley structures on the temperature dependent second peak field Hsp(T) and its associated onset field Hon(T) are revealed by the low temperature magnetization data. An analysis of the data on the basis of the cage model for point disorder induced effect shows an excellent fit of the data over the entire valley structure. Meanwhile, the magnetotransport data measured in the liquid phase temperature regime exhibit ~ H-1 behavior for the activation energy of thermally activated flux flow (TAFF). These data further confirm the existence of the theoretically predicted existence of disentangled vortex line liquid state.