Interplay of Paramagnetic Signal with Superconductive Environment in a (Nd,Eu,Gd)BaCuO Single Crystal

In LRE-Ba2Cu3Oy (LRE-123, LRE=Nd,Eu,Sm,Gd) superconductors paramagnetic signal of LRE atoms complicates evaluation of weak superconducting signals, like of the equilibrium reversible magnetization. While above Tc the superconductor follows Curie-Weiss (C-W) law, below Tc the measured reversible response above irreversibility field is a mixture of reversible magnetization and a paramagnetic background. A way to correct for the latter is an extrapolation of a pure paramagnetic response from temperatures well above Tc. We measured magnetic behavior of a weakly doped (Nd0.33Eu0.38Gd0.28)Ba2Cu3Oy single crystal from 300 K to 80 K. The reversible magnetization was successfully extracted, which enabled evaluation of the associated thermodynamic quantities for the given compound.