Ultrafast Dynamics of Electrons and Crystal Lattice in Bismuth Selenide

Abstract

We have studied the ultrafast response of a Bi₂Se₃ crystal to femtosecond laser pulses. We have observed an increase in the rise time of the electronic signal and the simultaneous increase in the amplitude of coherent phonons that occur when the central wavelength of the pump laser pulse is tuned from 1500 to 600 nm. These effects are interpreted as a result of screening of the electron–electron interaction by optical phonons.