We have measured the temperature dependence of the reversible magnetization of a four-layered cuprate TlBa2Ca3Cu4O y (Tl-1234) for the H∥c axis, which has the highest superconducting transition temperature Tc of almost 130 K among the four-layered cuprates. The reversible magnetization was analyzed by using the high-field scaling theory and the Hao-Clem model. It was found that in the critical region around Tc, two-dimensional fluctuations dominate. This enhanced 2D behavior can be naturally explained by selective doping model, where doping levels of the inner and outer CuO2 planes in a unit cell are different. From these analyses, various thermodynamic parameters, such as the coherence length, the penetration depth, the critical fields, and the Ginzburg-Landau parameter were obtained.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Sep 2004|