The effect of Cu substitution on the A1g mode of La0.7Sr0.3MnO3 manganites

We report on the first Raman data of Cu substituted La1−ySryMn1−xCuxO3 (0 ≤ x ≤ 0.10 and 0.17 ≤ y ≤ 0.3, accordingly in order to have the same Mn/[Mn+Mn] ratio), collected in the frequency range 100-900 cm and at room temperature, with parallel (ei ‖ es) and crossed (ei ⊥ es) polarizations of the incident (ei) and scattered (es) light. Spectra were fitted with a Drude-Lorentz model, and peaks at 190-220 and 430 cm, together with two broad structures centered at near 500 and 670 cm, have been found. We also have observed that the A1g mode is substantially shifted with increasing Cu substitution. The A1g phonon shift is a linear function of the tolerance factor t and the rhombohedral angle αr, thus following the structural changes of the MnO6 octahedra in the system.