Terahertz ellipsometry study of the soft mode behavior in ultrathin SrTiO films
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Marsik, Premysl
Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
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Sen, Kaushik
Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
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Khmaladze, Jarji
Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
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Yazdi-Rizi, Meghdad
Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
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Mallett, Benjamin P. P.
Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
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Bernhard, Christian
Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
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Published in:
- Applied Physics Letters. - 2016, vol. 108, no. 5, p. 052901
English
We present a combined study with time-domain terahertz and conventional far-infrared ellipsometry of the temperature dependent optical response of SrTiO₃thin films (82 and 8.5 nm) that are grown by pulsed-laser deposition on (La0.3Sr0.7) (Al0.65Ta0.35)O₃ (LSAT) substrates. We demonstrate that terahertz ellipsometry is very sensitive to the optical response of these thin films, in particular, to the soft mode of SrTiO₃. We show that for the 82 nm film the eigenfrequency of the soft mode is strongly reduced by annealing at 1200 °C, whereas for the 8.5 nm film it is hardly affected. For the latter, after annealing the mode remains at 125 cm⁻¹ at 300 K and exhibits only a weak softening to about 90 cm⁻¹ at 10 K. This suggests that this ultrathin film undergoes hardly any relaxation of the compressive strain due to the LSAT substrate.
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Faculty
- Faculté des sciences et de médecine
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Department
- Département de Physique
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Language
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Classification
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Physics
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License
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License undefined
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Identifiers
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Persistent URL
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https://folia.unifr.ch/unifr/documents/305194
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