Terahertz ellipsometry study of the soft mode behavior in ultrathin SrTiO<sub></sub> films

Marsik, Premysl; Sen, Kaushik; Khmaladze, Jarji; Yazdi-Rizi, Meghdad; Mallett, Benjamin P. P.; Bernhard, Christian

doi:10.1063/1.4940976

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Terahertz ellipsometry study of the soft mode behavior in ultrathin SrTiO films

Marsik, Premysl Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
Sen, Kaushik Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
Khmaladze, Jarji Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
Yazdi-Rizi, Meghdad Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
Mallett, Benjamin P. P. Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
Bernhard, Christian Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland

01.02.2016

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 (La_0.3Sr_{0.7) (Al_0.65Ta_0.35)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.}

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

Language

English

Classification

Physics

License

License undefined

Identifiers

RERO DOC 277707
DOI 10.1063/1.4940976

Persistent URL

https://folia.unifr.ch/unifr/documents/305194

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