Abstract
We present a detail study of Shubinikov-de-Haas (SdH) oscillations accompanied by conductance fluctuations in a mesoscopic topological insulator PbBi4Te7 device. From SdH oscillations, the evidence of Dirac fermions with π Berry phase is found and the experimentally determined two main Fermi wave vectors are correlated to two surface Dirac cones (buried one inside the other) of layered topological insulator PbBi4Te7. We have also found evidence of conductance fluctuations, the root mean square amplitude of which is much higher than the usual universal conductance fluctuations observed in nanometer size sample. Calculated autocorrelation functions indicate periodic unique fluctuations may be associated with the topological surface states in the compound.
Highlights
Block and seven-atomic layers of PbBi2Te4 block, separated by van-der-Waals gap
We present for the first time an exploration of the magneto-transport properties of nano device made from mechanically exfoliated flake of PbBi4Te7 single crystal, synthesized by modified Bridgman method
2 K, best described by: Rxx = R0 + βe−Tθ + γT 2 where, R0 is the residual resistance of the crystal
Summary
Rxx at 2, 10 and 50 K, black lines illustrates respectively. (b) Oscillatory the beat envelopes. Rxx at 2, 10 and 50 K, black lines illustrates respectively. 2 K, best described by: Rxx = R0 + βe−Tθ + γT 2 where, R0 is the residual resistance of the crystal. The exponential and quadratic terms represent electron-phonon and electron-electron interactions, respectively. The fitted parameters indicate the conduction at higher temperatures is assisted by electron-phonon scattering mainly whereas, the electron-electron interaction can be neglected. In the presence of magnetic field (B = 2 T and 5 T), the R0 value does not change considerably; R0 = 0.0104(7) Ω for B = 2 T and R0 = 0.0104(4) Ω for B = 5 T, respectively as illustrated, suggests absence of magnetic or spin dependent impurities in the crystal. The smoothed curves as illustrated, reveals an oscillatory nature of Rxx. For better contrast, derivative of the longitudinal conductivity ( ) ( ) Fig. 3(b) vs
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