Structural properties of (Nd0.33Eu0.2Gd0.47)Ba2Cu3Oy studied by magnetic and infrared measurements

Reflectance of a single crystal of the (Nd0.33Eu0.2Gd0.47)Ba2Cu3Oy superconductor was measured as a function of frequency from 35 to 8000 cm−1 and for temperatures from 10 to 300 K. The Kramers-Kronig analysis with appropriate extrapolations was used to calculate response functions. The AC conductivity displays phonons at frequencies typical for the whole family of REBa2Cu3Oy cuprates. The Drude term is rather low in comparison to optimally doped cuprates. The spectra were fitted to study temperature dependence of their parameters. DC electrical conductivity and magnetization were measured using a four-probe technique and a vibrating sample magnetometer, respectively. The remnant Jc reached 21.0 kA/cm2, Jc at the secondary peak was 20.0 kA/cm2 at 2.0 T.