VORTEX FLUCTUATION IN HGBA2CA3CU4O10+DELTA

Reversible magnetization with the external magnetic fields of 1 T less than or equal to H less than or equal to 5 T parallel to the c-axis h as been measured for the grain aligned HgBa2Ca3Cu4O10+delta. A strong vortex fluctuation effect was clearly observed and the magnetization i s well described by the vortex fluctuation model. From this analysis, the penetration depth lambda(ab)(0) = 1583 Angstrom and the effective interlayer spacing s = 44.6 Angstrom were estimated. However, the valu e of a is significantly larger than the lattice parameter c = 19 Angst rom, which is different from the prediction of the vortex fluctuation model. From the model on superconducting fluctuations proposed by Kosh elev, in which not only the critical fluctuations at the lowest Landau level but also the Gaussian fluctuations at higher Landau levels were considered, the different value of s = 15.4 Angstrom was obtained.