Study of Crystal Structure and Magnetics Properties in the Normal State of Electron-Doped Eu_2-xCe_xCu_0.97Zn_0.03O_4+α-δ in Overdoped Regime

The normal state of high-T_c superconducting cuprates is crucial to understanding of the mechanism in superconductivity. There are two main ways to remove superconductivity so that the sample is in a normal state, that is by applying a large magnetic field or adding impurities such as Zn to the sample. To investigate the crystal structure and magnetic properties in the normal state of electron-doped high-T_c cuprates in overdoped regime, Eu_2-xCe_xCu_0.97Zn_0.03O_4+α-δ (ECCZO) with x = 0.16, 0.17, 0.18, and 0.19 has been synthesized by the solid-state reaction method. The crystal structure and magnetic properties of the samples were characterized by XRD and SQUID measurements. The results of XRD measurements show all samples have T’-structure and the values of lattice parameters a, CuO bond length, and crystallite size increased with increasing x. On the other hand, the value of lattice parameters c decreased with increasing x, causing the expansion of the tetragonal unit cell in the horizontal direction. From susceptibility measurements, in the normal state with 3% of Zn impurity all samples have the paramagnetic behaviour. The magnetic parameters of these samples analysed by the Curie law. The Curie constant (C) and the effective magnetic moment (μ_eff) increased with increasing Ce concentration. It indicated an enhancement of magnetic ordering.