Backfolded acoustic phonons as ultrasonic probes in metal-oxide superlattices

ORAL

Abstract

Ultrasound has been widely used as an incisive probe of internal interfaces. For thin-film structures however, it is largely ineffective because the signal is dominated by the substrate. Using confocal Raman spectro-microscopy, we show that multiple reflection of sound waves at internal interfaces of a metal-oxide superlattice generates standing waves that are insensitive to the substrate. These backfolded acoustic phonon modes are sensitive to atomic-scale thickness variations of the sublayers and thus serve as a powerful characterization tool for metal-oxide superlattices.

*Supported by the SNF through Grant No.200020-172611, the Rutherford Foundation and the MacDiarmid Institute.

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Authors

  • Fryderyk Lyzwa

    • Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland

  • Andrew Chan

    • The MacDiarmid Institute for Advanced Materials and Nanotechnology, 1010 Auckland, New Zealand

  • Jarji Khmaladze

    • Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland

  • Katrin Fürsich

    • Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany

  • Bernhard Keimer

    • Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany

  • Christian Bernhard

    • Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland

  • Matteo Minola

    • Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany

  • Benjamin P. P. Mallett

    • The MacDiarmid Institute for Advanced Materials and Nanotechnology, 1010 Auckland, New Zealand