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arXiv · 1309.1405

Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi$_2$Se$_3$

Jonathan A. Sobota·Shuolong Yang·Alexander F. Kemper·J. J. Lee·Felix T. Schmitt·Wei Li·Robert G. Moore·James G. Analytis·Ian R. Fisher·Patrick S. Kirchmann·Thomas P. Devereaux·Zhi-Xun Shen
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Abstract

We characterize the occupied and unoccupied electronic structure of the topological insulator Bi$_2$Se$_3$ 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.

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Jonathan A. Sobota, Shuolong Yang, Alexander F. Kemper, J. J. Lee, Felix T. Schmitt, Wei Li, Robert G. Moore, James G. Analytis, Ian R. Fisher, Patrick S. Kirchmann, Thomas P. Devereaux, Zhi-Xun Shen. 2013-09-05. Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi$_2$Se$_3$. https://doi.org/10.1103/physrevlett.111.136802

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