The peak effect in magnetization loops of melt-processed (SmxEu1-x)Ba2Cu3O7-δ superconductors is manipulated by varying the Sm/Eu ratio in the initial composition. In all the samples the peak field BP(T), at which the magnetization moment reaches the maximum, was linearly temperature dependent. The fitting to such a relationship unveils a slightly lower critical temperature Tcp than the bulk Tc at zero field. A kink appears in the reversible magnetization moment of the field dependence of superconducting transition. This kink temperature Tck(B) is also a linear function of applied field. Transmission electron microscopy (TEM) observation confirms the presence of nano-scale regular compositional modulation arising from local RE-Ba substitution, which is weakened with increasing Eu concentration. The peak effect is thus attributed to the scattering of local Tc due to compositional fluctuation.
ASJC Scopus subject areas