Ultrafast carrier dynamics and light-induced functionalizations of topological insulators

Sumida, Kazuki   ; Ishida, Yukiaki*; Kimura, Akio*

By using time- and angle-resolved photoemission spectroscopy, we investigate the ultrafast carrier dynamics in the series of (Sb,Bi)Te. We show that the electronic recovery time for the surface Dirac fermions is prolonged to 400 ps when the charge neutrality point is approached. We also discuss the emergence of light-induced functionalizations such as surface photovoltage effect in the ultrafast time-domain. Our study strengthens the route toward the Dirac materials to be an opto-spintronic application.