Scaling behavior of conductivity and magnetization in high-temperature superconductors

Abstract

Through magnetization and conductivity measurements, the effect of dimensionality on the superconducting fluctuations has been investigated for ${\mathrm{Tl}}_{2}$ ${\mathrm{Ba}}_{2}$ ${\mathrm{CaCu}}_{2}$ ${\mathrm{O}}_{8}$ (Tl-2212), ${\mathrm{YBa}}_{2}$ ${\mathrm{Cu}}_{3}$ ${\mathrm{O}}_{7}$ (YBCO), and (Tl,Bi)${\mathrm{Si}}_{2}$ ${\mathrm{CaCu}}_{2}$ ${\mathrm{O}}_{7}$ (Tl-1212). Our results show that the bilayered thallium compound (i.e., Tl-2212 which is the most anisotropic compound) is clearly two-dimensional (2D) while a 3D-2D crossover is evidenced for Tl-1212 and YBCO. This crossover occurs through an intermediate region between two asymptotic behaviors: 3D near the transition and 2D at higher temperatures.