Gigantic surface lifetime of an intrinsic topological insulator

Madhab Neupane, Su-Yang Xu, Yukiaki Ishida, Shuang Jia, Benjamin M Fregoso, Chang Liu, Ilya Belopolski, Guang Bian, Nasser Alidoust, Tomasz Durakiewicz, Victor Mikhaylovich Galitskiy, Shik Shin, Robert J Cava, Md Zahid Hasan

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The interaction between light and novel two-dimensional electronic states holds promise to realize new fundamental physics and optical devices. Here, we use pump-probe photoemission spectroscopy to study the optically excited Dirac surface states in the bulk-insulating topological insulator Bi2Te2Se and reveal optical properties that are in sharp contrast to those of bulk-metallic topological insulators. We observe a gigantic optical lifetime exceeding 4μs (1μs=10-6s) for the surface states in Bi2Te2Se, whereas the lifetime in most topological insulators, such as Bi2Se3, has been limited to a few picoseconds (1ps=10-12s). Moreover, we discover a surface photovoltage, a shift of the chemical potential of the Dirac surface states, as large as 100 mV. Our results demonstrate a rare platform to study charge excitation and relaxation in energy and momentum space in a two-dimensional system.
Original languageEnglish
Article number116801
Pages (from-to)1-5
Number of pages5
JournalPhysical Review Letters
Issue number11
Publication statusPublished - 2015

Cite this

Neupane, M., Xu, S-Y., Ishida, Y., Jia, S., Fregoso, B. M., Liu, C., Belopolski, I., Bian, G., Alidoust, N., Durakiewicz, T., Galitskiy, V. M., Shin, S., Cava, R. J., & Hasan, M. Z. (2015). Gigantic surface lifetime of an intrinsic topological insulator. Physical Review Letters, 115(11), 1-5. [116801].