Magnetic fluctuations on TR sub(3)Ba sub(5)Cu sub(8)O sub() delta (TR=Ho, Y and Yb) superconducting system

In this work, we report the production of TR sub(3)Ba sub(5)Cu sub(8)O sub() delta (TR=Ho, Y and Yb) superconducting system using a usual solid state reaction method. The irreversibility line and the analysis of magnetization fluctuations for TR sub(3)Ba sub(5)Cu sub(8)O sub() delta (TR=Ho, Y and Yb) system were investigated. The curves of magnetization ZFC-FC were measured in magnetic fields of the 100-4000 Oe to obtain the values for T* and T sub(c)temperatures. The penetration depth and the coherence length parameters as a function of the applied magnetic field were obtained. The data of the magnetization excess Delta M(T, H) was analyzed from the curves of magnetization as a function of logarithm of applied field for different values of temperature in the corresponding range. The Bulavskii, Ledvij and Kogan theory was employed for this purpose which considers fluctuations effects in the free energy and into the equilibrium magnetization.