Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 43: Ultra-fast phenomena

HL 43.5: Vortrag

Mittwoch, 18. März 2015, 10:30–10:45, EW 202

Nonlinear Coupling of Phonons to Ferroelastic Domain Walls in SrTiO₃ Observed by Ultrafast Light Scattering from Phonons — •Lena Maerten, André Bojahr, Matthias Rössle, and Matias Bargheer — Insitut für Physik und Astronomie, Universität Potsdam, Germany

We excite high amplitude strain waves in SrTiO₃ (STO) using metal transducer films and monitor the strain propagation by ultrafast broadband transient reflectivity experiments. The phonon oscillations observed in temperature dependent measurements give access to the linear and nonlinear acoustic response of STO in the 100 GHz range across its ferroelastic transition. We interpret the linear response as a coupling to the ferroelastic soft mode and the nonlinear behaviour as a strain dependent coupling of phonons to ferroelastic domain walls [1]. We evaluate the wavevector dependent attenuation of the excited phonon modes and discuss, how the presence of domain walls affects the sound attenuation in STO in different temperature regimes.

[1] L. Maerten, A. Bojahr, M. Rössle, M. Gohlke and M. Bargheer, Coupling of GHz phonons to ferroelastic domain walls in SrTiO₃, Phys. Rev. Let., accepted