"Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3"

J. A. Sobota: S. Yang, J. G. Analytis, Y. L. Chen, I. R. Fisher, P. S. Kirchmann, Z.-X. Shen; Physical Review Letters, 03/14/12.

Additional Authors: S. Yang, J. G. Analytis, Y. L. Chen, I. R. Fisher, P. S. Kirchmann, Z.-X. Shen

Abstract:

Using femtosecond time- and angle-resolved photoemission spectroscopy, we investigated the nonequilibrium dynamics of the topological insulator Bi2Se3. We studied p-type Bi2Se3, in which the metallic Dirac surface state and bulk conduction bands are unoccupied. Optical excitation leads to a metastable population at the bulk conduction band edge, which feeds a nonequilibrium population of the surface state persisting for >10  ps. This unusually long-lived population of a metallic Dirac surface state with spin texture may present a channel in which to drive transient spin-polarized currents.