Temperature-dependent chirped coherent phonon dynamics in Bi$ {2}$Te$ {3}$ using high intensity femtosecond laser pulses - Condensed Matter > Materials ScienceReport as inadecuate




Temperature-dependent chirped coherent phonon dynamics in Bi$ {2}$Te$ {3}$ using high intensity femtosecond laser pulses - Condensed Matter > Materials Science - Download this document for free, or read online. Document in PDF available to download.

Abstract: Degenerate pump-probe reflectivity experiments have been performed on asingle crystal of bismuth telluride Bi$ 2$Te$ 3$ as a function of sampletemperature 3K to 296K and pump intensity using $\sim$ 50 femtosecond laserpulses with central photon energy of 1.57 eV. The time resolved reflectivitydata show two coherently generated totally symmetric A$ {1g}$ modes at 1.85 THzand 3.6 THz at 296K which blue shift to 1.9 THz and 4.02 THz, respectively at3K. At high photoexcited carrier density of $\sim$ 1.7 $\times$10$^{21}$cm$^{-3}$, the phonon mode at 4.02 THz is two orders of magnitudehigher positively chirped i.e the phonon time period decreases with increasingdelay time between the pump and the probe pulses than the lower frequency modeat 1.9 THz. The chirp parameter, $\beta$ is shown to be inversely varying withtemperature. The time evolution of these modes is studied using continuouswavelet transform of the time-resolved reflectivity data.



Author: N. Kamaraju, Sunil Kumar, A. K. Sood

Source: https://arxiv.org/







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