Remanent Magnetization in a Y_0.5Lu_0.5Ba₂Cu₃O_y Superconductor: Experimental Studies and Numerical Computations Using H-Formulation

Remanent magnetization of Y_0.5Lu_0.5Ba₂Cu₃O_y superconductor produced by a modified melt powder melt growth (MPMG) technique at 25 K temperature has been investigated by both experimental and numerical computations using H-formulation in the finite element method (FEM). At the low field and low-temperature conditions, remanent magnetization M_REM is equal to the difference between the field cooled magnetization M_FC and zero field cooled magnetization M_ZFC. Experimental data for remanent magnetization as a function of temperature can be reproduced quite well by numerical computations based on H-formulation providing an estimation of how the critical current density varies with temperature. The critical current density at 25 K was estimated to be a 6.50 × 10⁸ A/m², and the temperature dependence is determined as (1 − T/T_c)^2.5 from the best fit curve of M_REM(T) for the sample studied. In numerical calculations, we have used J_c(H) = J_c0/(1 + H/H_REF), where H_REF is a constant characterizing the superconducting sample. Furthermore, both flux density profile and current density profile have been obtained from the numerical calculations for various stages of the field applications or temperature values during the heating process.