Quantum capacitance in topological insulators

Faxian Xiu, Nicholas Meyer, Xufeng Kou, Liang He, Murong Lang, Yong Wang, Xinxin Yu, Alexei V. Fedorov, Jin Zou, Kang L. Wang

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

Topological insulators show unique properties resulting from massless, Dirac-like surface states that are protected by time-reversal symmetry. Theory predicts that the surface states exhibit a quantum spin Hall effect with counter-propagating electrons carrying opposite spins in the absence of an external magnetic field. However, to date, the revelation of these states through conventional transport measurements remains a significant challenge owing to the predominance of bulk carriers. Here, we report on an experimental observation of Shubnikov-de Haas oscillations in quantum capacitance measurements, which originate from topological helical states. Unlike the traditional transport approach, the quantum capacitance measurements are remarkably alleviated from bulk interference at high excitation frequencies, thus enabling a distinction between the surface and bulk. We also demonstrate easy access to the surface states at relatively high temperatures up to 60 K. Our approach may eventually facilitate an exciting exploration of exotic topological properties at room temperature.

Original languageEnglish
Article number669
JournalScientific reports
Volume2
DOIs
Publication statusPublished - 2012

All Science Journal Classification (ASJC) codes

  • General

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