Observation of chiral surface excitons in a topological insulator Bi2 Se3

Proceedings of the National Academy of Sciences of the United States of America
H-H KungG Blumberg

Abstract

The protected electron states at the boundaries or on the surfaces of topological insulators (TIs) have been the subject of intense theoretical and experimental investigations. Such states are enforced by very strong spin-orbit interaction in solids composed of heavy elements. Here, we study the composite particles-chiral excitons-formed by the Coulomb attraction between electrons and holes residing on the surface of an archetypical 3D TI, [Formula: see text] Photoluminescence (PL) emission arising due to recombination of excitons in conventional semiconductors is usually unpolarized because of scattering by phonons and other degrees of freedom during exciton thermalization. On the contrary, we observe almost perfectly polarization-preserving PL emission from chiral excitons. We demonstrate that the chiral excitons can be optically oriented with circularly polarized light in a broad range of excitation energies, even when the latter deviate from the (apparent) optical band gap by hundreds of millielectronvolts, and that the orientation remains preserved even at room temperature. Based on the dependences of the PL spectra on the energy and polarization of incident photons, we propose that chiral excitons are made from massive ho...Continue Reading

References

Oct 15, 1994·Physical Review. B, Condensed Matter·A VinattieriL J Sham
Apr 12, 2006·Physical Review Letters·A V Chaplik, L I Magarill
Apr 7, 2010·Physical Review Letters·S RaghuShou-Cheng Zhang
Mar 17, 2011·Physical Review Letters·D HsiehN Gedik
Jun 19, 2012·Nature Nanotechnology·Kin Fai MakTony F Heinz
Feb 7, 2013·Physical Review Letters·Mohammad KoleiniBinghai Yan
Aug 13, 2013·Nature Nanotechnology·Aaron M JonesXiaodong Xu
Dec 10, 2013·Physical Review Letters·Diana Y QiuSteven G Louie
Jun 3, 2017·Journal of Physics. Condensed Matter : an Institute of Physics Journal·D BuginiE Carpene
Jan 18, 2018·Physical Review Letters·H-H KungG Blumberg
May 11, 2019·Physical Review Letters·H SoiferZ-X Shen

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Citations

Sep 5, 2020·Scientific Reports·K HoltgreweC Carbone
May 11, 2019·Physical Review Letters·H SoiferZ-X Shen
Dec 18, 2019·Nature Communications·Yasen HouDong Yu

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