Structural properties of the epitaxial CuCr_0.95Mg _0.05O₂ thin films on c-plane sapphire substrates by pulsed laser deposition

We report an investigation of the structural properties of CuCr _0.95Mg_0.05O₂ films on c-plane sapphire substrates using pulsed laser deposition. The thin films were grown at different temperatures of 500, 600, and 700 °C with an oxygen partial pressure of 10 mTorr. c-axis oriented epitaxial CuCr_0.95Mg_0.05O ₂ thin films on c-plane sapphire substrates with an in-plan 30° rotation were obtained. The sixfold rotational symmetry in the pole figures from the (0 1 2) plane indicates that there are two different types of crystal grains in which the a-axes rotate by 60° with respect to each other around the c-axis. The reason for the 30° rotation is assumed to be the presence of the ∼10% mismatch of oxygen distance between the c-plane sapphire substrate and the CuCr_0.95Mg_0.05O₂ on the c-plane. The epitaxial crystallographic relationship between CuCr_0.95Mg _0.05O₂ and Al₂O₃ was (0 0 0 6)CuCrO₂//(0 0 0 3)Al₂O₃ and [1 0 -1 0]CuCrO₂//[1 1 -2 0]Al₂O₃. The presence of twins in the films and the surface morphology were investigated using transmission electron microscopy and scanning electron microscopy, respectively.