Abstract
We report the experimental observation of variable range hopping conduction in focused-ion-beam (FIB) fabricated ultra-narrow nanowires of topological insulator (Bi2Se3). The value of the exponent (d + 1)−1 in the hopping equation was extracted as sim frac{1}{2},,for different widths of nanowires, which is the proof of the presence of Efros-Shklovskii hopping transport mechanism in a strongly disordered system. High localization lengths (0.5 nm, 20 nm) were calculated for the devices. A careful analysis of the temperature dependent fluctuations present in the magnetoresistance curves, using the standard Universal Conductance Fluctuation theory, indicates the presence of 2D topological surface states. Also, the surface state contribution to the conductance was found very close to one conductance quantum. We believe that our experimental findings shed light on the understanding of quantum transport in disordered topological insulator based nanostructures.
Highlights
Quantum transport through topological insulator (TI) based nanostructures is among the most widely pursued research in recent condensed matter studies
The details of the fabrication process are given in the Methods section
In order to understand the effect of perpendicular magnetic field on the resistance of the FIB fabricated Bi2Se3 nanowire, first we have removed the contribution of UCF by smoothing the M-R curve
Summary
Quantum transport through topological insulator (TI) based nanostructures is among the most widely pursued research in recent condensed matter studies. Some theoretical models have focused on the effect of impurities, adatoms, strong electronic correlations and disorder on topological phase transition, electronic band structure, shifting of Dirac point due to induced surface potential, spin-orbit interaction and TSS conductance[20,21,22,23,24,25], a very few experimental studies were performed on disordered and non-uniformly surfaced TI samples, which keep the electrical transport mechanism in such systems an interesting issue of discussion. Is observed very close to 1 for different widths of the nanowires indicating the no dependence on the dimensionality, i.e. the proof of the[2] Efros-Shklovskii (ES-) VRH mechanism, which has been usually demonstrated in strongly disordered systems at low temperatures[39,40,41]
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