Remanent Magnetization in a Y0.5Lu0.5Ba2Cu3Oy Superconductor: Experimental Studies and Numerical Computations Using H-Formulation

Remanent magnetization of Y0.5Lu0.5Ba2Cu3Oy 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 x 10(8) A/m(2), 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.