Characterization of high-T sub(c) superconductors using the higher-harmonic susceptibility

In the present work, the harmonic magnetic susceptibilities of the high-T sub(c ) superconductors are examined and corresponding harmonic susceptibilities are calculated employing a model by Kim and coworkers. According to Kim's model, the critical-current density, J sub(c) is a function of the internal magnetic field H sub(i), J sub(c)(H) = k/(H sub(o) + |H sub(i)|) where k and H sub(o) are constants. In the model calculations, full penetrations field, H sub(p), is taken to be H sub(o)[(1 + p super(2)) super(1/2) - 1] where p = (2 ka) super(1/2 )/ H sub(o). As a result of the comparison of model calculations with experiments, we conclude that the harmonic susceptibilities for lower p values (p < 10) correspond to the similar characteristic magnetic behaviour of granular superconductors, while the harmonic susceptibilities for higher p values correspond to the behaviour of homogeneous superconductors such as single crystal or samples with contiguous oriented grains.