Coherent lattice dynamics of the topological insulator Bi2Te3 probed by ultrafast spectroscopy

Femtosecond laser pulses have been used to excite coherent optical phonons in single crystalline Bi2Te3. Oscillations from low and high frequency phonons of two A(1g) and one E-g symmetry modes are observed. In order to clarify the process of coherent phonon generation, the time domain measurements were complemented by spontaneous Raman scattering. The comparison of frequency and time domain results reveals the discrepancies between the time and frequency domain measurements among which the most striking difference is given by the fact that the E-g((I)) phonon is missing in the time domain data. (C) 2014 AIP Publishing LLC.