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arXiv · 1508.06000

Gigantic surface life-time of an intrinsic topological insulator revealed via time-resolved (pump-probe) ARPES

Madhab Neupane·Su-Yang Xu·Yukiaki Ishida·Shuang Jia·Benjamin M. Fregoso·Chang Liu·Ilya Belopolski·Guang Bian·Nasser Alidoust·Tomasz Durakiewicz·Victor Galitski·Shik Shin·Robert J. Cava·M. Zahid Hasan
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Abstract

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 life-time exceeding 4 micro-sec for the surface states in Bi2Te2Se, whereas the life-time in most topological insulators such as Bi2Se3 has been limited to a few picoseconds. Moreover, we discover a surface photo-voltage in topological materials, 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 quantum system.

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Madhab Neupane, Su-Yang Xu, Yukiaki Ishida, Shuang Jia, Benjamin M. Fregoso, Chang Liu, Ilya Belopolski, Guang Bian, Nasser Alidoust, Tomasz Durakiewicz, Victor Galitski, Shik Shin, Robert J. Cava, M. Zahid Hasan. 2015-08-25. Gigantic surface life-time of an intrinsic topological insulator revealed via time-resolved (pump-probe) ARPES. https://doi.org/10.1103/physrevlett.115.116801

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