Twinning and lattice distortions in the epitaxy of La0.67Sr0.33MnO3 thin films on (001) SrTiO3

We study the epitaxy of La0.67Sr0.33MnO3 (LSMO) thin films on SrTiO3 (STO) (0 0 I) 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 degrees) 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. (C) 2001 Elsevier Science B.V. All rights reserved.