Abstract :
The dynamics of phonons in a Bi2Se3 crystal has been studied by using femtosecond time-resolved reflection measurements. Two coherent optical phonons with A 1 g 1 and A 1 g 2 modes are observed at 2.14 and 5.09 THz at room temperature, respectively. The initial amplitude of the generated coherent A 1 g 2 phonons is higher than that of the A 1 g 1 phonons, but those are quickly damped with a rate of 1.28 THz.
