Experimental and theoretical Raman study on the HTSC [formula omitted] family for different Pr concentrations and synthesis methods

Abstract

We present a joint study of confocal Raman spectroscopy, supported by the oretical simulations, together with resistivity and X-ray diffraction measurements on the high temperature superconductor (HTSC) YBa2Cu3O7 family doped with Pr atoms. The samples are grown using two different synthesis routes: sol–gel and solid-state reaction. Samples produced by both methods present similar structural and morphological properties but small differences are observed in their superconductive properties and vibrational response. The latter is correlated with ab-initio simulations for different concentrations of Pr. We find that as the Pr concentration increases, the presence of a forbidden B1u mode is enhanced. This is explained by a loss of the centrosymmetric symmetry when Pr is present. The different effects in the Raman modes with Pr content are explained by the change of interatomic distances in the inner cell. Finally, the good correlation obtained between experimental Raman spectra and ab-intio calculations validated the latter, allowing to study the evolution of the electronic band structure as a function of Pr content and ionic radii. Once again, we explained the difference observed by the changes in the atoms distribution inside the unit cell.