Direct observation of Dirac states in Bi2Te3 nanoplatelets by 125Te NMR

TL;DR

This study uses advanced 125Te NMR techniques combined with DFT calculations to directly observe and analyze how Dirac electrons in Bi2Te3 nanoplatelets extend from the surface into the bulk, providing atomic-scale insights.

Contribution

It introduces a novel NMR approach to detect and characterize Dirac surface states in topological insulators at atomic resolution, complementing existing spectroscopic methods.

Findings

Detected NMR signals influenced by Dirac electrons

Mapped the extension of Dirac electrons into the nanoplatelet bulk

Provided atomic-scale understanding of surface-bulk electron interactions

Abstract

Detection of the metallic Dirac electronic states on the surface of Topological Insulators (TIs) is a tribune for a small number of experimental techniques the most prominent of which is Angle Resolved Photoemission Spectroscopy. However, there is no experimental method showing at atomic scale resolution how the Dirac electrons extend inside TI systems. This is a critical issue in the study of important surface quantum properties, especially topological quasiparticle excitations. Herein, by applying advanced DFT-assisted solid-state 125Te Nuclear Magnetic Resonance on Bi2Te3 nanoplatelets, we succeeded in uncovering the hitherto invisible NMR signals with magnetic shielding influenced by the Dirac electrons, and subsequently showed how Dirac electrons spread and interact with the bulk interior of the nanoplatelets.