Gate-Tunable Surface States in Topological Insulator β-Ag<sub>2</sub>Te with High Mobility.

Leng, Pengliang; Chen, Fangting; Cao, Xiangyu; Wang, Yuxiang; Huang, Ce; Sun, Xuandong; Yang, Yaozhi; Zhou, Junchen et al. · Nano Lett · 2020

basic_science · Level V

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Abstract

Stimulated by novel properties in topological insulators, experimentally realizing quantum phases of matter and employing control over their properties have become a central goal in condensed matter physics. β-silver telluride (Ag<sub>2</sub>Te) is predicted to be a new type narrow-gap topological insulator. While enormous efforts have been plunged into the topological nature in silver chalcogenides, sophisticated research on low-dimensional nanostructures remains unexplored. Here, we report the record-high bulk carrier mobility of 298 600 cm<sup>2</sup>/(V s) in high-quality Ag<sub>2</sub>Te nanoplates and the coexistence of the surface and bulk state from systematic Shubnikov-de Haas oscillations measurements. By tuning the correlation between the top and bottom surfaces, we can effectively enhance the contribution of the surface to the total conductance up to 87% at 130 V. These results are instrumental to the high-mobility physics study and even suitable to explore exotic topological phenomena in this material system.