Hypersound studies of the electron doped Ln2−xCexCuO4 and hole doped La2−xMxCuO4 high-Tc single crystals

Abstract

Here we report the growth of the electron doped HTSC Ln 2− x Ce x CuO 4 ( Ln = Gd , Eu , Nd , Pr ; x =0, 0.15) single crystals and room temperature measurements of their hypersound surface acoustic wave (SAW) velocities V SAW . Mandelstamm-Brillouin light scattering was used to the determination of the V SAW values in (001) crystal planes. SAW velocities of the hole doped La 2− x M x CuO 4 ( M = Ca , Sr , Ba ; 0 ⩽ x ⩽ 0.15) crystals were also measured. For both type of crystals V SAW is constant for all the azimuths of the SAW vector in the (001) plane. In the case of Ln 2−x Ce x CuO 4 crystals the V SAW value rises ≈20% with the Ln radii increase from Gd to Pr.