Large bulk resistivity and surface quantum oscillations in the topological insulatorBi2Te2Se

Abstract

Topological insulators are predicted to present interesting surface transport phenomena but their experimental studies have been hindered by a metallic bulk conduction that overwhelms the surface transport. We show that the topological insulator Bi 2 Te 2 Se presents a high resistivity exceeding 1 ⍀ cm and a variable-range hopping behavior, and yet presents Shubnikov-de Haas oscillations coming from the topological surface state. Furthermore, we have been able to clarify both the bulk and surface transport channels, establishing a comprehensive understanding of the transport in this material. Our results demonstrate that Bi 2 Te 2 Se is, to our knowledge, the best material to date for studying the surface quantum transport in a topological insulator.

Magneto-transport behaviour of Bi2Se3−xTex: role of disorder

“…Interestingly, the emergence of two carrier transports in figure 5 (b), correlates with the presence of transition from positive to negative magneto-resistance in figure 5 (a). Such non-linear behaviour has already been observed in similar TI samples and is reported to be due to the parallel contribution of both surface and bulk carrier to the transport [13,15,17,23].…”

“…Figure 3 shows the Hall resistance as a function of magnetic field at various temperatures in the pristine and Te doped samples. In the pristine Bi 2 Se 3 sample, Hall resistance is linear with magnetic field and is nearly temperature independent (see figure 3 (a) figure 3 (c)-(d)), the Hall resistance shows a non-linear behaviour with respect to applied magnetic field at low T, suggestive of presence of transport from two types of carriers [13]. Effect measurements (cf.…”

“…Therefore, alloying these end compounds compensates the bulk defect states and result in a bulk insulating state as it is observed in Bi 2 SeTe 2 ternary [13]. Our earlier studies in Bi 2 Se 3 with excess Se, had clearly indicated that, stacking faults which has formed due to excess Se seem favourable in the manifestation of the surface state in the transport behaviour [14].…”

Growth of High-Mobility Bi2Te2Se Nanoplatelets on hBN Sheets by van der Waals Epitaxy

“…Bi 2 Te 2 Se has emerged as one of the most promising TIs due to its simple surface band structure, large bulk band gap and low bulk contribution to the total charge transport 16,20,21 . Our Bi 2 Te 2 Se films grown by van der Waals epitaxy are sufficiently ordered to display Shubnikov-de Haas (SdH) oscillations which provide access to important quantities such as the cyclotron mass, the Fermi velocity or Fermi energy 23 .…”

“…12,14 Moreover, the results of low temperature Hall measurements performed at different back gate voltages (see Supplementary Information), are consistent with the n-doped character of our samples. 20,21,22 . It is furthermore noteworthy that the Hall mobilities agree well with the values extracted from the SdH oscillations for -60V < V g < 20V (see Supplementary Information).…”