Large-amplitude chirped coherent phonons in tellurium mediated by ultrafast photoexcited carrier diffusion

Details Large-amplitude chirped coherent phonons in tellurium mediated by ultrafast photoexcited carrier diffusion Large-amplitude chirped coherent phonons in tellurium mediated by ultrafast photoexcited carrier diffusion

2010-10-30

arxiv.org/abs/1011.0090v1

Physics

Condensed Matter

Materials Science

22 pages, 6 figures, submitted to PRB

Scientific paper

We report femtosecond time-resolved reflectivity measurements of coherent phonons in tellurium performed over a wide range of temperatures (3K to 296K) and pump laser intensities. A totally symmetric A$_{1}$ coherent phonon at 3.6 THz responsible for the oscillations in the reflectivity data is observed to be strongly positively chirped (i.e, phonon time period decreases at longer pump-probe delay times) with increasing photoexcited carrier density, more so at lower temperatures. We show for the first time that the temperature dependence of the coherent phonon frequency is anomalous (i.e, increasing with increasing temperature) at high photoexcited carrier density due to electron-phonon interaction. At the highest photoexcited carrier density of $\sim$ 1.4 $\times$ 10$^{21}$cm$^{-3}$ and the sample temperature of 3K, the lattice displacement of the coherent phonon mode is estimated to be as high as $\sim$ 0.24 \AA. Numerical simulations based on coupled effects of optical absorption and carrier diffusion reveal that the diffusion of carriers dominates the non-oscillatory electronic part of the time-resolved reflectivity. Finally, using the pump-probe experiments at low carrier density of 6 $\times$ 10$^{18}$ cm$^{-3}$, we separate the phonon anharmonicity to obtain the electron-phonon coupling contribution to the phonon frequency and linewidth.

Affiliated with

Also associated with

No associations

Rating

Large-amplitude chirped coherent phonons in tellurium mediated by ultrafast photoexcited carrier diffusion does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Large-amplitude chirped coherent phonons in tellurium mediated by ultrafast photoexcited carrier diffusion, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Large-amplitude chirped coherent phonons in tellurium mediated by ultrafast photoexcited carrier diffusion will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-405379