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 Galitski, Shik Shin, Robert J. Cava, M. Zahid Hasan

Research output: Contribution to journalArticlepeer-review

85 Scopus citations


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 (US)
Article number116801
JournalPhysical review letters
Issue number11
StatePublished - Sep 9 2015

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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