Ultrafast Energy- and Momentum-resolved Surface Dirac Photocurrents in the Topological Insulator Sb${}_2$Te${}_3$

Abstract

We present energy-momentum mapping of surface Dirac photocurrent in the topological insulator Sb${}_2$Te${}_3$ by means of time- and angle-resolved two-photon photoemission spectroscopy combined with polarization-variable mid-infrared pulse laser. It is demonstrated that the direct optical transition from the occupied to the unoccupied part of the surface Dirac-cone permits the linear and circular photogalvanic effect which thereby enables us to coherently control the surface electric-current by laser polarization. Moreover, the surface current mapping directly visualizes ultrafast current dynamics in the Dirac cone in the time domain. We unravel the ultrafast intraband relaxation dynamics of the inelastic scattering and momentum scattering separately. Our observations pave the pathway for coherent optical control over surface Dirac electrons in topological insulators.

References in corpus (8)

• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3
• Ultrafast surface carrier dynamics in the topological insulator Bi2Te3
• Direct Measurement of the Out-of-Plane Spin Texture in the Dirac Cone Surface State of a Topological Insulator
• Ultrafast helicity control of surface currents in topological insulators with near-unity fidelity
• Ultrafast carrier and phonon dynamics in Bi2Se3 crystals
• Ultrafast photodoping and effective Fermi-Dirac distribution of the Dirac particles in Bi2Se3
• Coherent control over three-dimensional spin polarization for the spin-orbit coupled surface state of Bi${}_2$Se${}_3$

Cited by in corpus (3)

• Tuning time and energy resolution in time-resolved photoemission spectroscopy with nonlinear crystals
• High-frequency nonlinear transport and photogalvanic effects in two-dimensional topological insulators
• A narrow bandwidth extreme ultra-violet light source for time- and angle-resolved photoemission spectroscopy