Twinning and lattice distortions in the epitaxy of La0.67Sr0.33MnO3 thin films on (0 0 1) SrTiO3

We study the epitaxy of La0.67Sr0.33MnO3 (LSMO) thin films on SrTiO3 (STO) (0 0 1) by pulsed laser deposition (PLD). In addition to a lattice mismatch of 0.82%, ferromagnetic LSMO is rhombohedral (pseudo-cubic with an angle of 90.26°) while STO is cubic. We measure lattice distortions using quantitative high resolution electron microscopy (HRTEM). For low thickness far below the critical one, such distortions allow a partial recovery of the original rhombohedral symmetry of LSMO [R. Lyonnet et al., Appl. Surf. Sci. 162–163 (2000) 245]. Here, we present observations of layers of various thickness and further characterisation of this phenomenon as a function of misorientation of the substrate surface.