Abstract
BaTiO 3 /SrTiO 3 superlattices were grown on (001)MgO substrates by pulsed-laser-deposition technique. The thickness of each layer varied from 6 to 25 unit cells. Polarization-dependent Raman spectra confirmed tetragonal symmetry of the superlattices with the polar axis being normal to the layers. The observed optic modes in the superlattices showed intermediate frequencies between corresponding bulk BaTiO 3 and SrTiO 3 values, while the E(TO 1 ) soft mode exhibited upward shift due to significant two-dimensional clamping caused by the lattice mismatch of the constituting layers. The observed downward shift of the soft mode revealed relaxation of two-dimensional stresses with increasing the stacking periodicity of the superlattices. The excitation of folded transverse acoustic phonons in the Raman spectra due to the new periodicity of the Brillouin zone was revealed. The observed data are quantitatively explained by a folding of the corresponding acoustic branch. It is shown that micro-Raman spectroscopy provides determination of a spatial variation of the layer thickness in graded superlattices. On leave from the Faculty of Physics, Rostov State University, Rostov-on-Don, Russia
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
