Abstract-Anisotropy of the infrared-active phonon modes in the mono-domain state of tetragonal SrTiO3 (110)

M. Yazdi-Rizi, P. Marsik, B. P. P. Mallett, C. Bernhard

(Submitted on 8 Aug 2016)

http://arxiv.org/abs/1608.02329

With infrared and terahertz ellipsometry we investigated the anisotropy of the infrared active phonon modes in SrTiO3 (110) single crystals in the tetragonal state below the so-called antiferrodistortive transition at T* = 105 K. In particular, we show that the anisotropy of the oscillator strength of the so-called R-mode, which becomes weakly infrared active below T*, is a valuable indicator for the orientation of the structural domains. Our results reveal that a mono-domain state with the tetragonal axis (c-axis) parallel to the [001] direction can be created by applying a moderate uniaxial stress of about 2.3 MPa along the [1-10] direction (with a mechanical clamp). The resulting, intrinsic splitting of the infrared-active phonon modes is reported.