Heterostructures of La Sr MnO rSrTiO rLa Sr MnO 0.67 0.33 3 3 0.67 0.33 3 grown by pulsed laser deposition on 001/ SrTiO3

We have prepared by pulsed laser deposition La0.67Sr0.33MnO3 LSMO.rSrTiO3 STO.rLSMO tunnel junctions epitaxially grown on 001.STO. LSMO is rhombohedral in bulk pseudo cubic with an angle of 89.748.; its epitaxy on STO raises two kinds of questions: 1. are the interfaces chemically abrupt? 2. How is the geometrical mismatch rhombohedron on cube. accommodated? We have investigated these issues using cross-sectional high-resolution transmission electron microscopy HRTEM.. We have shown previously that interdiffusion was absent, and that interfacial roughness was restricted to single unit cell steps wJ.-L. Maurice, R. Lyonnet, J.-P. Contour, J. Mag. Mag. Mat. 211 2000.91x. Here, we present our results on atomic plane distortion measurements using quantitative Fourier analysis of the HRTEM micrographs. We show that a progressive twinning occurs that gives a full rhombohedral relaxation at a thickness of about 30 nm, with no need of dislocations. q2000 Elsevier Science B.V. All rights reserved