Behaviour of Paramagnetic Light Rare Earth Ions in LRE-123 Superconductors

The slightly curved paramagnetic background (due to Brillouin dependence) of the paramagnetic light rare earth ions in 123 superconductors mixes below Tc with reversible magnetization, which hinders evaluation of the associated thermodynamic characteristics. We propose a method how to determine the effective number of magnetons per ion, the principal parameter of the Brillouin function course, even in materials with pores, with unknown or varying density and/or the local composition. The method was tested on various types of compounds containing Gd ions, like pure Gd-211, tetragonal Gd-123, (Y,Gd)-123, and (Nd,Eu,Gd)- 123 and on orthorhombic (oxygenated) Gd-123 and (Nd,Eu,Gd)-123.