Lightwave-driven Dirac currents in a topological surface band
Controlling spin polarized carriers on a subcycle time scale may enable spintronics at optical clock rates. Angle-resolved photoemission spectroscopy with subcycle time resolution has successfully visualized how the carrier wave of a terahertz light pulse accelerates Dirac fermions in the band structure of the topological surface state. The inertia-free surface currents are protected by spin-momentum locking and reach peak densities as large as two amps per centimetre, with ballistic mean free paths of several hundreds of nanometres, opening up an avenue to optical clock spintronics. This article describes our recent observation of light-wave driven Dirac currents in a topological insulator after briefly introducing basic concepts and recent applications of topological insulators.
- 1 Department of Physical Science, Graduate School of Science, Hiroshima University