Electron-Hole Asymmetry of Surface States in Topological Insulator Sb<sub>2</sub>Te<sub>3</sub> Thin Films Revealed by Magneto-Infrared Spectroscopy.

Jiang, Yuxuan; Asmar, Mahmoud M; Han, Xingyue; Ozerov, Mykhaylo; Smirnov, Dmitry; Salehi, Maryam; Oh, Seongshik; Jiang, Zhigang et al. · Nano Lett · 2020

basic_science · Level V

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Abstract

When surface states (SSs) form in topological insulators (TIs), they inherit the properties of bulk bands, including the electron-hole (e-h) asymmetry but with much more profound impacts. Here via combining magneto-infrared spectroscopy with theoretical analysis, we show that e-h asymmetry significantly modifies the SS electronic structures when interplaying with the quantum confinement effect. Compared with the case without e-h asymmetry, the SSs now bear not only a band asymmetry, such as that in the bulk, but also a shift of the Dirac point relative to the bulk bands and a reduction of the hybridization gap of up to 70%. Our results signify the importance of e-h asymmetry in the band engineering of TIs in the thin-film limit.