Magnetic Properties and Superconductivity of YBa₂(Cu_1-xFe_x)₃O_y

Abstract

Magnetic properties of YBa 2 (Cu 1- x Fe x ) 3 O y ( x =0.05∼0.15, y ≃7) were investigated by magnetometry and Mössbauer spectroscopy. The temperature dependence of the susceptibility of the sample with x =0.15 (not superconducting) exhibited a cusp which is explained as the evidence of spin glass transition. Mössbauer spectra at low temperatures exhibited hyperfine splitting, whether the sample was superconducting or not. We suggest that the magnetic splittings come from spin glass, not from paramagnetic slow relaxation phenomena.