The Paramagnetism Carried by Paramagnetic Ions and its Effect on the Superconductivity in High TC Superconductors

Extended Brillouin function with a revision is applied to describe the paramagnetism carried by the rare-earth Gd^{3 +} ions in GdBa₂Cu₃O₆₊ and the Re²⁺ ions in (Hg_0.9Re_0.1)Ba₂Ca₂Cu₃O_g+. We believe that the paramagnetism depends on the internal flux density of the sample instead of the applied field. At the field below H_cl the paramagnetism has no contribution to total magnetization; at the field over H_cl the paramagnetic magnetization has different values when in field-increasing and field-decreasing process. The width of the magnetization hysteresis loop M is broadened by the paramagnetism. The effect of the paramagnetism due to paramagnetic ions on the magnetization relaxation rate and the magnetization critical-current density J_c based on the Bean critical-state model is also discussed. The temperature dependence of the paramagnetism is shown in this paper.