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In their comment to our paper 1 on the observation of anomalous acoustic phonon dispersion in SrTiO3 (STO), Devos et al. 2 present results obtained by stimulated Brillouin scattering on the very same system (STO (001) capped with Al) over an extended probe wavelength range. By using a different setup employing distinct probe wavelengths (kpr) from a tunable Ti: sapphire oscillator in the 370–510nm range, they found a substantial disagreement with our data around 440 nm for the frequency of oscillation (f) of the differential reflectivity, which is related to the sound speed (vs) by the formula: f ¼ ð2nðkprÞ/kprÞvsðkprÞ, where n is the refractive index of STO. On the other hand Devos et al. found a nice agreement with the expected behaviour for f in case of linear acoustic phonon dispersion, which corresponds to a constant sound speed.Stimulated by this comment, we built up a new broadband picosecond …
American Institute of Physics
Publication date: 
14 May 2012

Stefano Brivio, Dario Polli, Andrea Crespi, R Osellame, G Cerullo, Riccardo Bertacco

Biblio References: 
Volume: 100 Issue: 20 Pages: 206101
Applied Physics Letters