Strains in Fe/Cr/Fe trilayers and (Fe/Cr)5/Fe multilayers epitaxied on MgO and MgO/SrTiO3

Fe/Cr/Fe trilayers and multilayers are prepared as model systems designed to furnish simple data comparable with calculation results for diffusion properties in nuclear materials. Their structure (epitaxy, residual strains and dislocations) is characterized in detail. The film structure (strain and stress) is shown to be different on MgO20nm/SrTiO3 and MgO substrates due to the residual strain in the MgO buffer layer on SrTiO3. Superlattices with high crystalline quality are prepared, with Fe and Cr in coherent epitaxy. In-plane residual strain in Fe is +0.45(13)% on MgO substrates and decreases from 1.70(9)% to 0.47(2)% when increasing the thickness of the trilayers on MgO/SrTiO3 substrates. These strains enhance the contrast between Fe and Cr, opening the way to future kinetics studies using x-ray diffraction in this system, which is far more efficient (non-destructive and rapid) than high resolution transmission electron microscopy with electron energy loss spectroscopy or atom probe tomography