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Ultrafast surface Dirac fermion dynamics of Sb$$_2$$Te$$_3$$-based topological insulators

Sumida, Kazuki   ; Ishida, Yukiaki*; G$"u$dde, J.*; H$"o$fer, U.*; Shin, S.*; Kimura, Akio*

Topological insulators (TIs) characterized by gapless and spin-polarized band dispersion on their surfaces have been extensively studied over the last decade. This article reviews our recent works on ultrafast carrier dynamics of Sb$$_2$$Te$$_3$$-based nonmagnetic and magnetic TIs by utilizing state-of-the-art femtosecond time- and angle-resolved photoelectron spectroscopy. We have demonstrated that the electronic recovery time elongated from a few ps to $$>$$ 400 ps in the series of (Sb$$_{1-x}$$Bi$$_x$$)$$_2$$Te$$_3$$. We also investigated how the magnetic-impurity affects the carrier dynamics in ferromagnetic Sb$$_{2-y}$$V$$_y$$Te$$_3$$. It was found that the electronic recovery time drastically shortened from a few ps to $$<$$ 500 fs with increasing vanadium concentration. Since the lifetime of the nonequilibrated surface Dirac fermions can range from femto- to nano-second, Sb$$_2$$Te$$_3$$-based TIs would be promising for ultrafast spin switching and spin-polarized current generation device applications.



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Category:Chemistry, Physical



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