Tuning the quantum oscillations of surface Dirac electrons in the topological insulator Bi2Te2Se by liquid gating

Jun Xiong, Yuehaw Khoo, Shuang Jia, R. J. Cava, N. P. Ong

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In Bi2Te2Se, the period of quantum oscillations arising from surface Dirac fermions can be increased sixfold using ionic liquid gating. At high gate voltages, the Fermi energy reaches the N=1 Landau level in a 14-T field. This enables the 12 shift predicted for the Dirac spectrum to be measured accurately. A surprising result is that liquid gating strongly enhances the surface mobility. By analyzing the Hall conductivity, we show that the enhancement occurs on only one surface. We present evidence that the gating process is fully reversible (hence consistent with band bending by the E field from the anion layer accumulated). In addition to the surface carriers, the experiment yields the mobility and density of the bulk carriers in the impurity band. By analyzing the charge accumulation vs gate voltage, we also obtain estimates of the depletion width and the areal depletion capacitance C d/A. The value of Cd/A implies an enhanced electronic polarizability in the depletion region.

Original languageEnglish (US)
Article number035128
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number3
StatePublished - Jul 22 2013

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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