Backfolded acoustic phonons as ultrasonic probes in metal-oxide superlattices

Lyzwa, Fryderyk; Chan, A.; Khmaladze, Jarji; Fürsich, K.; Keimer, B.; Bernhard, Christian; Minola, M.; Mallett, Benjamin P. P.

doi:10.1103/PhysRevMaterials.4.043606

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Journal article

Backfolded acoustic phonons as ultrasonic probes in metal-oxide superlattices

Lyzwa, Fryderyk Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
Chan, A. The MacDiarmid Institute for Advanced Materials and Nanotechnology and The Dodd Walls Centre for Quantum and Photonic Technologies, 1010 Auckland, New Zealand - School of Chemical Sciences, The University of Auckland, 1010 Auckland, New Zealand
Khmaladze, Jarji Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
Fürsich, K. Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
Keimer, B. Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
Bernhard, Christian Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Chemin du Musée 3, CH-1700 Fribourg, Switzerland
Minola, M. Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
Mallett, Benjamin P. P. The MacDiarmid Institute for Advanced Materials and Nanotechnology and The Dodd Walls Centre for Quantum and Photonic Technologies, 1010 Auckland, New Zealand - Department of Physics, The University of Auckland, 1010 Auckland, New Zealand

28.04.2020

Published in:

Physical Review Materials. - 2020, vol. 4, no. 4, p. 043606

English Ultrasonics have been an incisive probe of internal interfaces in a wide variety of systems ranging from stars to solids. For thin-film structures, however, ultrasound is largely ineffective because the signal is dominated by the substrate. Using confocal Raman spectromicroscopy, 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. Such modes had previously been observed only in high-quality superlattices of elemental semiconductors, and their observation in complex metal- oxide heterostructures is testimony to recent progress in this field. We use the high spatial resolution of the Raman microscope to demonstrate the high sensitivity of the mode frequency to atomic-scale thickness variations of the superlattice. Spectroscopy of acoustic standing waves can hence serve as a powerful characterization tool of thin-film structures. In analogy to ultrasound spectroscopy of bulk solids, lineshape analysis of these modes has the potential to yield detailed information about the internal structure of the interfaces as well as the coupling of sound waves to the low- frequency spin, charge, and orbital dynamics in metal-oxide superlattices.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

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