Band structure of topological insulators from noise measurements in tunnel junctions

TL;DR

This study uses tunneling and noise spectroscopy in TI/Al₂O₃/Co junctions to reveal band structure features of topological insulators through conductance and noise measurements, aiding their application in spintronics.

Contribution

It demonstrates that noise measurements can effectively identify band structure features in topological insulators, simplifying their analysis for spintronic device development.

Findings

Band structure features appear in tunneling conductance.

Low frequency noise peaks correspond to band features.

Noise spectroscopy provides a clear probe of TI band structure.

Abstract

The unique properties of spin-polarized surface or edge states in topological insulators (TIs) make these quantum coherent systems interesting from the point of view of both fundamental physics and their implementation in low power spintronic devices. Here we present such a study in TIs, through tunneling and noise spectroscopy utilizing TI/Al$_2$O$_3$/Co tunnel junctions with bottom TI electrodes of either Bi$_2$Te$_3$ or Bi$_2$Se$_3$. We demonstrate that features related to the band structure of the TI materials show up in the tunneling conductance and even more clearly through low frequency noise measurements. The bias dependence of 1/f noise reveals peaks at specific energies corresponding to band structure features of the TI. TI tunnel junctions could thus simplify the study of the properties of such quantum coherent systems, that can further lead to the manipulation of their spin-polarized properties for technological purposes.