Magnetic-Relaxation Behavior of (Tl0.5Pb0.5)(Sr1.84Nd0.16)CaCu2O7 Superconducting Material

We report experimental studies of the time deacy of the nonequilibrium magnetization, a phenomenon known as magnetic relaxation. in a polycrystalline high-temperature superconductor (Tl0.5Pb0.5)(Sr1.84Nd0.16)CaCu2O7 with T-c = 105 K. The temperature dependence of the relaxation rate defined as A = d[M(t) - M-eq]/d ln(t) has been sketched for this material at a wide range of temperatures for applied fields of 1, 2, 3 and 10 kOe. Analysis of Arrhenius plots yields two field-dependence average pinning energies in the temperature range 5-70 K, reflecting two regimes of relaxation behavior. The relaxation rate approaches zero at the irreversibility line which can be described by the scaling relation H(T*) = H-o(1-T*/T-c)(n) with n similar to 2.0 for H less than or equal to 10 kOe.