Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 89: Optical Properties II

HL 89.3: Talk

Friday, March 18, 2011, 10:45–11:00, POT 251

A simulated reflectivity experiment: theoretical optical spectrum of strained-lattice bulk SrTiO3 — •Lorenzo Sponza^1,2, Valérie Véniard^1,2, Adriano Verna³, and Stefano Nannarone^3,4 — ¹LSI - Ecole Polytechnique, 91128 Palaiseau, France — ²European Theoretical Spectroscopy Facility (ETSF) — ³IOM-CNR lab. TASC Area Science Park, Basovizza, Italy — ⁴Università di Modena e Reggio Emilia, Italy

Reflectivity and absorption measurements are powerful techniques to investigate microscopic properties of matter as structural configuration. An interpretation of measured data can be given through the macroscopic dielectric constant, even if such an interpretation is complicated.

Here we present a theoretical study carried on the optical properties of bulk SrTiO3 (STO) with two different lattice structures: one is the cubic structure (a=3.905 Angstrom) and one is a strained configuration. We present the computation of the macroscopic dielectric tensor of STO performed in the framework of Time Dependent Density Functional Theory (TDDFT) and Many Body Perturbation Theory (MBPT) in the G0W0 approximation and solving Bethe-Salpeter equation. Comparison with experimental data has been also carried out.

Using a C++ code written ad hoc to compute the reflectivity of anisotropic materials, we will display the difference in signal due to the structural strain and we will link it to the difference between the two theoretical dielectric tensors.