Ultrafast dynamics in topological insulators

C. W. Luo; H.-J. Chen; H. J. Wang; S. A. Ku; K. H. Wu; T. M. Uen; J. Y. Juang; J.-Y. Lin; B. L. Young; T. Kobayashi; R. Sankar; F. C. Chou; H. Berger; G. D. Gu

doi:10.1117/12.2001954

14 March 2013 Ultrafast dynamics in topological insulators

C. W. Luo, H.-J. Chen, H. J. Wang, S. A. Ku, K. H. Wu, T. M. Uen, J. Y. Juang, J.-Y. Lin, B. L. Young, T. Kobayashi, R. Sankar, F. C. Chou, H. Berger, G. D. Gu

Author Affiliations +

Proceedings Volume 8623, Ultrafast Phenomena and Nanophotonics XVII; 86230D (2013) https://doi.org/10.1117/12.2001954
Event: SPIE OPTO, 2013, San Francisco, California, United States

Abstract

Ultrafast dynamics of carriers and phonons in topological insulators Cu_xBi₂Se_3-y (x=0, 0.1, 0.125, y=0, 1) was studied using femtosecond optical pump-probe spectroscopy. One damped oscillation was clearly observed in the transient reflectivity changes (ΔR/R), which is assigned to the coherent optical phonon (A_1g ¹). According to the red shift of A_1g¹ phonon frequency, the Cu atoms in Cu_xBi₂Se₃ crystals may predominantly intercalated between pair of the quintuple layers. Moreover, the carrier dynamics in the Dirac-cone surface state is significantly different from that in bulk state, which was investigated using optical pump mid-infrared (mid-IR) probe spectroscopy. The rising time and decay time of the negative component in ΔR/R, which is assigned to carrier relaxation in Dirac cone, is 1.62 ps and 20.5 ps, respectively.

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C. W. Luo, H.-J. Chen, H. J. Wang, S. A. Ku, K. H. Wu, T. M. Uen, J. Y. Juang, J.-Y. Lin, B. L. Young, T. Kobayashi, R. Sankar, F. C. Chou, H. Berger, and G. D. Gu "Ultrafast dynamics in topological insulators", Proc. SPIE 8623, Ultrafast Phenomena and Nanophotonics XVII, 86230D (14 March 2013); https://doi.org/10.1117/12.2001954

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