Ultrafast surface Dirac fermion dynamics of SbTe-based topological insulators

角田 一樹; 石田 行章*; Gdde, J.*; Hfer, U.*; Shin, S.*; 木村 昭夫*

Progress in Surface Science, 96(2), p.100628_1 - 100628_15, 2021/05

https://doi.org/10.1016/j.progsurf.2021.100628

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 SbTe-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 (SbBi)Te. We also investigated how the magnetic-impurity affects the carrier dynamics in ferromagnetic SbVTe. 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, SbTe-based TIs would be promising for ultrafast spin switching and spin-polarized current generation device applications.