Vortex-Lattice Melting in Tl(Sr1.5R0.5)CaCu2O7-y (R = Nd, Sm, and Eu) System

M. F. Tai；W. H. Lee

Chinese Journal of Physics

36卷2S期（1998 / 04 / 01）

262 - 268

英文

The partial substitution Sr of by a rare earth element R (except Pm) in TlSr2CaCu2O7-y, oxide has been successfully carried out. Measurements of X-ray diffraction and dc magnetic susceptibility show that all they exhibit well-defined superconductivity with the TlSr2CaCu2O7-y, structure and Tc ~ 90 K for all rare earths except Pm. In this study, the irreversibility lines Hi,.,.(T) of three polycrystalline high-T, superconductors T1(Sr1.5R0.5)CaCu2O7-y with R = Nd, Sm and Eu were studied in a field range H 5 10 kOe. The experimental data of the Hi,.,.(T) 1'me for each sample is well fitted to a three-dimensional-like power-law relation: Hirr(T) = Hirr(0)[1-T/Tmo]^2. Based on the nonlocal elasticity theory using Lindemann criterion, the power function with the exponent approximating to 2 is interpreted as the occurrence of the thermally activated vortex-lattice melting in sample.