Excitation and detection of high-frequency coherent acoustic phonons in low-symmetry superlattices

Walker, P. M.; Campion, R. P.; Kent, A. J.; Lehmann, D.; Jasiukiewicz, Cz.

doi:10.1103/physrevb.78.233307

Cited by 10 publications

(10 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The acoustic-mode coherent vibration of the lattice causes modulation of the reflection, with a frequency determined by the phonon energy. [43][44][45][46][47][48][49][50][51][52][53][54][55][56] The frequency corresponds to an energy of 0.14 meV. Unlike in other materials where many periods of oscillation are usually observed, [43][44][45][46][47][48][49][50][51][52][53][54][55][56] only one to two periods are observed here.…”

Section: Coherent Acoustic Phononsmentioning

confidence: 52%

Spatially resolved femtosecond pump-probe study of topological insulator Bi2Se3

et al. 2011

View full text Add to dashboard Cite

Carrier and phonon dynamics in Bi 2 Se 3 crystals are studied by a spatially resolved ultrafast pump-probe technique. Pronounced oscillations in differential reflection are observed with two distinct frequencies and are attributed to coherent optical and acoustic phonons, respectively. The rising time of the signal indicates that the thermalization and energy relaxation of hot carriers are both sub-ps in this material. We found that the thermalization and relaxation time decreases with the carrier density. The expansion of the differential reflection profile allows us to estimate an ambipolar carrier diffusion coefficient on the order of 500 cm 2 /s. A long-term slow expansion of the profile shows a thermal diffusion coefficient of 1.2 cm 2 /s.

show abstract

Section: Coherent Acoustic Phononsmentioning

confidence: 52%

Spatially resolved femtosecond pump-probe study of topological insulator Bi2Se3

et al. 2011

View full text Add to dashboard Cite

show abstract

“…16 In recent years, adaptations of this method to GHz shear wave generation through impulsive laser interaction have been developed. [17][18][19][20][21][22][23][24][25][26][27] Studies of shear waves in liquids, however, have remained elusive; 28 this is because it is generally much easier to monitor sound waves that are associated with local density variations than pure shear.…”

Section: Introductionmentioning

confidence: 99%

Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

Klieber

Hecksher

Pézeril

et al. 2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

This paper presents and discusses the temperature and frequency dependence of the longitudinal and shear viscoelastic response at MHz and GHz frequencies of the intermediate glass former glycerol and the fragile glass former tetramethyl-tetraphenyl-trisiloxane (DC704). Measurements were performed using the recently developed time-domain Brillouin scattering technique, in which acoustic waves are generated optically, propagated through nm thin liquid layers of different thicknesses, and detected optically after transmission into a transparent detection substrate. This allows for a determination of the frequency dependence of the speed of sound and the sound-wave attenuation. When the data are converted into mechanical moduli, a linear relationship between longitudinal and shear acoustic moduli is revealed, which is consistent with the generalized Cauchy relation. In glycerol, the temperature dependence of the shear acoustic relaxation time agrees well with literature data for dielectric measurements. In DC704, combining the new data with data from measurements obtained previously by piezo-ceramic transducers yields figures showing the longitudinal and shear sound velocities at frequencies from mHz to GHz over an extended range of temperatures. The shoving model's prediction for the relaxation time's temperature dependence is fairly well obeyed for both liquids as demonstrated from a plot with no adjustable parameters. Finally, we show that for both liquids the instantaneous shear modulus follows an exponential temperature dependence to a good approximation, as predicted by Granato's interstitialcy model.

show abstract

“…The generation of coherent THz vibrations is attributed to a number of physical mechanisms, including the photoelastic effect and deformation potential. 17,18 Depending on the pump photon energy, ប⍀ p , the first or the second of these may play a dominant role in generation of Raman c modes. The generation of the specific e mode may be considered in a similar way to the detection process described above.…”

mentioning

confidence: 99%