Optically detecting the edge-state of a three-dimensional topological insulator under ambient conditions by ultrafast infrared photoluminescence spectroscopy

Abstract

Ultrafast infrared photoluminescence spectroscopy was applied to a three-dimensional topological insulator TlBiSe2 under ambient conditions. The dynamics of the luminescence exhibited bulk-insulating and gapless characteristics bounded by the bulk band gap energy. The existence of the topologically protected surface state and the picosecond-order relaxation time of the surface carriers, which was distinguishable from the bulk response, were observed. Our results provide a practical method applicable to topological insulators under ambient conditions for device applications.

Zero-bias photocurrent in ferromagnetic topological insulator

“…In addition to intensive optical spectroscopy 20 21 22 23 24 25 26 27 , a number of photoeffects in TIs have been studied both theoretically and experimentally; photocurrent generation and galvanic effects 28 29 30 31 32 , carrier/spin dynamics elaborated by time-resolved optics 33 34 35 36 37 38 39 40 41 , photoemission 42 43 44 45 46 47 48 49 50 51 and the Floquet state 52 , including the cases of thin films with magnetic dopants 53 54 , to name a few. For the photocurrent generation at the normal incidence, it is predicted that the orbital coupling of light, that is, ħ → ħ − e , provides a predominant contribution to the polarization-independent photocurrent under an in-plane external magnetic field 17 .…”