2013/09/05 by Jonathan A. Sobota, Shuolong Yang, A. F. Kemper +17 · 1 citation
Materials Science · Physics and Astronomy · #2D Materials and Applications #Graphene research and applications #Topological Materials and Phenomena #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevlett.111.136802
published as Phys. Rev. Lett. 111, 136802 (2013) · Accepted to Physical Review Letters
arxiv created 2013/09/05 · openalex publication_date 2013/09/24 · arxiv updated 2013/11/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We characterize the occupied and unoccupied electronic structure of the topological insulator Bi2Se3 by one-photon and two-photon angle-resolved photoemission spectroscopy and slab band structure calculations. We reveal a second, unoccupied Dirac surface state with similar electronic structure and physical origin to the well-known topological surface state. This state is energetically located 1.5 eV above the conduction band, which permits it to be directly excited by the output of a Ti:sapphire laser. This discovery demonstrates the feasibility of direct ultrafast optical coupling to a topologically protected, spin-textured surface state.